Resist composition and method of forming resist pattern

ABSTRACT

A resist composition including a polymeric compound having a structural unit in which a compound represented by formula (a0-1) has a polymerizable group within the W1 portion converted into a main chain, and a compound represented by formula (b1-1) in which W1 represents a polymerizable group-containing group; Ct represents a tertiary carbon atom, and the α-position of Ct is a carbon atom which constitutes a carbon-carbon unsaturated bond; R11 represents an aromatic hydrocarbon group or a chain hydrocarbon group; R12 and R13 are mutually bonded to form a 5-membered aliphatic monocyclic group, or a condensed polycyclic hydrocarbon group containing a 5-membered aliphatic monocyclic ring; Rb11 represents a cyclic group; Rb10, Rb20 and Rb30 each independently represents a substituent; nb1 represents an integer of 0 to 4; nb2 represents an integer of 0 to 5; nb3 represents an integer of 0 to 5; and X− represents a counteranion.

TECHNICAL FIELD

The present invention relates to a resist composition and a method offorming a resist pattern.

Priority is claimed on Japanese Patent Application No. 2018-207774,filed Nov. 2, 2018, the content of which is incorporated herein byreference.

DESCRIPTION OF RELATED ART

In lithography techniques, for example, a resist film composed of aresist material is formed on a substrate, and the resist film issubjected to selective exposure, followed by development, therebyforming a resist pattern having a predetermined shape on the resistfilm. A resist material in which the exposed portions of the resist filmbecome soluble in a developing solution is called a positive-type, and aresist material in which the exposed portions of the resist film becomeinsoluble in a developing solution is called a negative-type.

In recent years, in the production of semiconductor elements and liquidcrystal display elements, advances in lithography techniques have led torapid progress in the field of pattern miniaturization. Typically, theseminiaturization techniques involve shortening the wavelength (increasingthe energy) of the exposure light source. Conventionally, ultravioletradiation typified by g-line and i-line radiation has been used, butnowadays KrF excimer lasers and ArF excimer lasers are used in massproduction. Furthermore, research is also being conducted intolithography techniques that use an exposure light source having awavelength shorter (energy higher) than these excimer lasers, such aselectron beam (EB), extreme ultraviolet radiation (EUV), and X ray.

Resist materials for use with these types of exposure light sourcesrequire lithography properties such as a high resolution capable ofreproducing patterns of minute dimensions, and a high level ofsensitivity to these types of exposure light sources.

As a resist material that satisfies these conditions, a chemicallyamplified composition is used, which includes a base material componentthat exhibits a changed solubility in a developing solution under theaction of acid and an acid-generator component that generates acid uponexposure.

For example, in the case where the developing solution is an alkalideveloping solution (alkali developing process), a chemically amplifiedpositive resist which contains, as a base component (base resin), aresin which exhibits increased solubility in an alkali developingsolution under action of acid, and an acid generator is typically used.If a resist film formed using such a resist composition is selectivelyexposed at the time of forming a resist pattern, in exposed areas, acidis generated from the acid generator component, and the polarity of thebase resin increases by the action of the generated acid, thereby makingthe exposed areas of the resist film soluble in the alkali developingsolution. Thus, by conducting alkali developing, the unexposed portionsof the resist film remain to form a positive resist pattern.

On the other hand, when such a base resin is applied to a solventdeveloping process using a developing solution containing an organicsolvent (organic developing solution), the solubility of the exposedportions in an organic developing solution is decreased. As a result,the unexposed portions of the resist film are dissolved and removed bythe organic developing solution, and a negative resist pattern in whichthe exposed portions of the resist film are remaining is formed. Such asolvent developing process for forming a negative-tone resistcomposition is sometimes referred to as “negative-tone developingprocess”.

In general, the base resin used for a chemically amplified resistcomposition contains a plurality of structural units for improvinglithography properties and the like.

For example, in the case of a resin composition which exhibits increasedsolubility in an alkali developing solution by the action of acid, astructural unit containing an acid decomposable group which isdecomposed by the action of acid generated from an acid generatorcomponent and exhibits increased polarity. Further, a structural unitcontaining a lactone-containing cyclic group or a structural unitcontaining a polar group such as a hydroxy group is used in combination.

Further, in the formation of a resist pattern, the behavior of acidgenerated from the acid generator component upon exposure is one of thefactors which has large influence on the lithography properties.

As the acid generator used in a chemically amplified resist composition,various kinds have been proposed. For example, onium salt acidgenerators such as iodonium salts and sulfonium salts; oxime sulfonateacid generators; diazomethane acid generators; nitrobenzylsulfonate acidgenerators; iminosulfonate acid generators; and disulfone acidgenerators are known.

As onium salt acid generators, those which have an onium ion such astriphenylsulfonium in the cation moiety are mainly used. Generally, asthe anion moiety for onium salt acid generators, an alkylsulfonate ionor a fluorinated alkylsulfonate ion in which part or all of the hydrogenatoms within the aforementioned alkylsulfonate ion has been substitutedwith fluorine atoms is typically used.

Further, in order to improve lithography properties in the formation ofa resist pattern, an onium salt acid generator having an anion with aspecific structure containing an aromatic ring as the anion moiety hasbeen proposed (for example, see Patent Literature 1).

DOCUMENTS OF RELATED ART Patent Literature

[Patent Literature 1] Japanese Patent No. 5149236

SUMMARY OF THE INVENTION

As the lithography technique further progresses and the miniaturizationof the resist pattern progresses more and more, for example, a target ofthe lithography performed by electron beams and EUV is to form fineresist patterns of several tens of nanometers. As the size of the resistpattern becomes smaller, the resist composition is required to havehigher sensitivity to the exposure light source and better lithographyproperties such as resolution and roughness reduction.

However, in the case of a resist composition containing a conventionalonium salt acid generator, when it is attempted to enhance thesensitivity of the resist composition to an exposure light source suchas EUV, there is a problem that it is difficult to obtain a desiredresist pattern shape or the like. Therefore, it was difficult to satisfyboth the sensitivity of the resist composition and the resist patternshape.

The present invention takes the above circumstances into consideration,with an object of providing a resist composition which exhibits improvedsensitivity and lithography properties, and which is capable of forminga resist pattern having a good shape; and a method of forming a resistpattern using the resist composition.

For solving the above-mentioned problems, the present invention employsthe following aspects.

Specifically, a first aspect of the present invention is a resistcomposition which generates acid upon exposure and exhibits changedsolubility in a developing solution under action of acid, the resistcomposition including a resin component (A1) which exhibits changedsolubility in a developing solution under action of acid and an acidgenerator component (B) which generates acid upon exposure, the resincomponent (A1) including a polymer having a structural unit (a0) inwhich a compound represented by general formula (a0-1) has apolymerizable group within the W¹ portion converted into a main chain,and the acid generator component (B) includes a compound represented bygeneral formula (b1-1) shown below.

In formula (a0-1), W¹ represents a polymerizable group-containing group;C^(t) represents a tertiary carbon atom, and the α-position of C^(t) isa carbon atom which constitutes a carbon-carbon unsaturated bond; R¹¹represents an aromatic hydrocarbon group which may have a substituent,or a chain hydrocarbon group; R¹² and R¹³ are mutually bonded to form a5-membered aliphatic monocyclic group optionally having a substituent,or a condensed polycyclic hydrocarbon group containing a 5-memberedaliphatic monocyclic ring, the condensed polycyclic hydrocarbon groupoptionally having a substituent; in formula (b1-1), R^(b11) represents acyclic group which may have a substituent; R^(b10), R^(b20) and R^(b30)each independently represents a substituent; n_(b1) represents aninteger of 0 to 4; n_(b2) represents an integer of 0 to 5; n_(b3)represents an integer of 0 to 5; and X⁻ represents a counteranion.

A second aspect of the present invention is a method of forming a resistpattern, including: using a resist composition according to the firstaspect to form a resist film, exposing the resist film, and developingthe exposed resist film to form a resist pattern.

According to the resist composition and method of forming the resistpattern of the present invention, sensitivity may be enhanced, and aresist pattern exhibiting improved lithography properties and having agood shape may be formed.

DETAILED DESCRIPTION OF THE INVENTION

In the present description and claims, the term “aliphatic” is arelative concept used in relation to the term “aromatic”, and defines agroup or compound that has no aromaticity.

The term “alkyl group” includes linear, branched or cyclic, monovalentsaturated hydrocarbon, unless otherwise specified. The same applies forthe alkyl group within an alkoxy group.

The term “alkylene group” includes linear, branched or cyclic, divalentsaturated hydrocarbon, unless otherwise specified.

A “halogenated alkyl group” is a group in which part or all of thehydrogen atoms of an alkyl group is substituted with a halogen atom.Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

A “fluorinated alkyl group” or a “fluorinated alkylene group” is a groupin which part or all of the hydrogen atoms of an alkyl group or analkylene group have been substituted with a fluorine atom.

The term “structural unit” refers to a monomer unit that contributes tothe formation of a polymeric compound (resin, polymer, copolymer).

The case of describing “may have a substituent” includes both of thecase where the hydrogen atom (—H) is substituted with a monovalent groupand the case where the methylene group (—CH₂—) is substituted with adivalent group.

The term “exposure” is used as a general concept that includesirradiation with any form of radiation.

The term “base component” refers to an organic compound capable offorming a film, and is preferably an organic compound having a molecularweight of 500 or more. When the organic compound has a molecular weightof 500 or more, the film-forming ability is improved, and a resistpattern of nano level can be easily formed. The organic compound used asthe base component is broadly classified into non-polymers and polymers.In general, as a non-polymer, any of those which have a molecular weightin the range of 500 to less than 4,000 is used. Hereafter, a “lowmolecular weight compound” refers to a non-polymer having a molecularweight in the range of 500 to less than 4,000. As a polymer, any ofthose which have a molecular weight of 1,000 or more is generally used.Hereafter, a “resin” or a “polymer” refers to a polymer having amolecular weight of 1,000 or more. As the molecular weight of thepolymer, the weight average molecular weight in terms of the polystyreneequivalent value determined by gel permeation chromatography (GPC) isused.

A “structural unit derived from an acrylate ester” refers to astructural unit that is formed by the cleavage of the ethylenic doublebond of an acrylate ester.

An “acrylate ester” refers to a compound in which the terminal hydrogenatom of the carboxy group of acrylic acid (CH₂═CH—COOH) has beensubstituted with an organic group.

The acrylate ester may have the hydrogen atom bonded to the carbon atomon the α-position substituted with a substituent. The substituent(R^(α0)) that substitutes the hydrogen atom bonded to the carbon atom onthe α-position is an atom other than hydrogen or a group, and examplesthereof include an alkyl group of 1 to 5 carbon atoms and a halogenatedalkyl group of 1 to 5 carbon atoms. Further, an acrylate ester havingthe hydrogen atom bonded to the carbon atom on the α-positionsubstituted with a substituent (R^(α0)) in which the substituent hasbeen substituted with a substituent containing an ester bond (e.g., anitaconic acid diester), or an acrylic acid having the hydrogen atombonded to the carbon atom on the α-position substituted with asubstituent (R^(α0)) in which the substituent has been substituted witha hydroxyalkyl group or a group in which the hydroxy group within ahydroxyalkyl group has been modified (e.g., α-hydroxyalkyl acrylateester) can be mentioned as an acrylate ester having the hydrogen atombonded to the carbon atom on the α-position substituted with asubstituent. A carbon atom on the α-position of an acrylate ester refersto the carbon atom bonded to the carbonyl group, unless specifiedotherwise.

Hereafter, an acrylate ester having the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent issometimes referred to as “α-substituted acrylate ester”. Further,acrylate esters and α-substituted acrylate esters are collectivelyreferred to as “(α-substituted) acrylate ester”.

A “structural unit derived from acrylamide” refers to a structural unitthat is formed by the cleavage of the ethylenic double bond ofacrylamide.

The acrylamide may have the hydrogen atom bonded to the carbon atom onthe α-position substituted with a substituent, and may have either orboth terminal hydrogen atoms on the amino group of acrylamidesubstituted with a substituent. A carbon atom on the α-position of anacrylamide refers to the carbon atom bonded to the carbonyl group,unless specified otherwise.

As the substituent which substitutes the hydrogen atom on the α-positionof acrylamide, the same substituents as those described above for thesubstituent (R^(α0)) on the α-position of the aforementioned α-positionof the aforementioned α-substituted acrylate ester can be mentioned.

A “structural unit derived from hydroxystyrene” refers to a structuralunit that is formed by the cleavage of the ethylenic double bond ofhydroxystyrene. A “structural unit derived from a hydroxystyrenederivative” refers to a structural unit that is formed by the cleavageof the ethylenic double bond of a hydroxystyrene derivative.

The term “hydroxystyrene derivative” includes compounds in which thehydrogen atom at the α-position of hydroxystyrene has been substitutedwith another substituent such as an alkyl group or a halogenated alkylgroup; and derivatives thereof. Examples of the derivatives thereofinclude hydroxystyrene in which the hydrogen atom of the hydroxy grouphas been substituted with an organic group and may have the hydrogenatom on the α-position substituted with a substituent; andhydroxystyrene which has a substituent other than a hydroxy group bondedto the benzene ring and may have the hydrogen atom on the α-positionsubstituted with a substituent. Here, the α-position (carbon atom on theα-position) refers to the carbon atom having the benzene ring bondedthereto, unless specified otherwise.

As the substituent which substitutes the hydrogen atom on the α-positionof hydroxystyrene, the same substituents as those described above forthe substituent on the α-position of the aforementioned α-substitutedacrylate ester can be mentioned.

A “structural unit derived from vinylbenzoic acid or a vinylbenzoic acidderivative” refers to a structural unit that is formed by the cleavageof the ethylenic double bond of vinylbenzoic acid or a vinylbenzoic acidderivative.

The term “vinylbenzoic acid derivative” includes compounds in which thehydrogen atom at the α-position of vinylbenzoic acid has beensubstituted with another substituent such as an alkyl group or ahalogenated alkyl group; and derivatives thereof. Examples of thederivatives thereof include benzoic acid in which the hydrogen atom ofthe carboxy group has been substituted with an organic group and mayhave the hydrogen atom on the α-position substituted with a substituent;and benzoic acid which has a substituent other than a hydroxy group anda carboxy group bonded to the benzene ring and may have the hydrogenatom on the α-position substituted with a substituent. Here, theα-position (carbon atom on the α-position) refers to the carbon atomhaving the benzene ring bonded thereto, unless specified otherwise.

The term “styrene derivative” includes compounds in which the hydrogenatom at the α-position of styrene has been substituted with anothersubstituent such as an alkyl group or a halogenated alkyl group; andderivatives thereof. Examples of the derivatives thereof includehydroxystyrene which has a substituent other than a hydroxy group bondedto the benzene ring and may have the hydrogen atom on the α-positionsubstituted with a substituent. Here, the α-position (carbon atom on theα-position) refers to the carbon atom having the benzene ring bondedthereto, unless specified otherwise.

A “structural unit derived from styrene” or “structural unit derivedfrom a styrene derivative” refers to a structural unit that is formed bythe cleavage of the ethylenic double bond of styrene or a styrenederivative.

As the alkyl group as a substituent on the α-position, a linear orbranched alkyl group is preferable, and specific examples include alkylgroups of 1 to 5 carbon atoms, such as a methyl group, an ethyl group, apropyl group, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group and a neopentylgroup.

Specific examples of the halogenated alkyl group as the substituent onthe α-position include groups in which part or all of the hydrogen atomsof the aforementioned “alkyl group as the substituent on the α-position”are substituted with halogen atoms. Examples of the halogen atom includea fluorine atom, a chlorine atom, a bromine atom and an iodine atom, anda fluorine atom is particularly desirable.

Specific examples of the hydroxyalkyl group as the substituent on theα-position include groups in which part or all of the hydrogen atoms ofthe aforementioned “alkyl group as the substituent on the α-position”are substituted with a hydroxy group. The number of hydroxy groupswithin the hydroxyalkyl group is preferably 1 to 5, and most preferably1.

In the present specification and claims, some structures represented bychemical formulae may have an asymmetric carbon, such that an enantiomeror a diastereomer may be present. In such a case, the one formularepresents all isomers. The isomers may be used individually, or in theform of a mixture.

(Resist Composition)

The resist composition according to a first aspect of the presentinvention is a resist composition which generates acid upon exposure andexhibits changed solubility in a developing solution under action ofacid, the resist composition including a base component (A) whichexhibits changed solubility in a developing solution under action ofacid (hereafter, also referred to as “component (A)”), and an acidgenerator component (B) which generates acid upon exposure (hereafter,also referred to as “component (B)”).

One embodiment of the resist composition is a resist compositioncontaining the component (A) and the component (B). Preferably, theresist composition contains, in addition to the component (A) and thecomponent (B), a basic component (hereafter, sometimes referred to as“component (D)”) which is capable of trapping acid generated from thecomponent (B) upon exposure (i.e., capable of controlling diffusion ofacid).

In the resist composition according to the present embodiment, thecomponent (A) contains a resin component (A1) (hereafter, referred to as“component (A1)”) which exhibits changed solubility in a developingsolution by the action of acid.

When a resist film is formed using the resist composition according tothe present embodiment and the formed resist film is subjected to aselective exposure, acid is generated at exposed portions, and thegenerated acid acts on the component (A1) to change the solubility ofthe component (A1) in a developing solution, whereas the solubility ofthe component (A1) in a developing solution is not changed at unexposedportions, thereby generating difference in solubility in a developingsolution between exposed portions and unexposed portions. Therefore, bysubjecting the resist film to development, the exposed portions of theresist film are dissolved and removed to form a positive-tone resistpattern in the case of a positive resist, whereas the unexposed portionsof the resist film are dissolved and removed to form a negative-toneresist pattern in the case of a negative resist.

In the present specification, a resist composition which forms apositive resist pattern by dissolving and removing the exposed portionsof the resist film is called a positive resist composition, and a resistcomposition which forms a negative resist pattern by dissolving andremoving the unexposed portions of the resist film is called a negativeresist composition.

The resist composition of the present embodiment may be either apositive resist composition or a negative resist composition. Further,in the present embodiment, the resist composition may be applied to analkali developing process using an alkali developing solution in thedeveloping treatment, or a solvent developing process using a developingsolution containing an organic solvent (organic developing solution) inthe developing treatment, and preferably a solvent developing process.

The resist composition of the present embodiment has a function ofgenerating acid upon exposure, and the component (A) may generate acidupon exposure, in addition to the component (B).

In the case where the component (A) generates acid upon exposure, thecomponent (A) is a “base component which generates acid upon exposureand exhibits changed solubility in a developing solution under action ofacid”.

In the case where the component (A) is a base component which generatesacid upon exposure and exhibits changed solubility in a developingsolution under action of acid, the aforementioned component (A1) ispreferably a polymeric compound which generates acid upon exposure andexhibits changed solubility in a developing solution under action ofacid. As the polymeric compound, a resin having a structural unit whichgenerates acid upon exposure may be mentioned. As the structural unitwhich generates acid upon exposure, any conventionally known structuralunit may be used.

<Component (A)>

In the resist composition of the present embodiment, the component (A)is a base component which exhibits changed solubility in a developingsolution under action of acid, and contains the aforementioned component(A1). By using the component (A1), the polarity of the base componentbefore and after exposure is changed. Therefore, a good developmentcontrast may be achieved not only in an alkali developing process, butalso in a solvent developing process.

More specifically, in the case of applying an alkali developing process,the base component containing the component (A1) is hardly soluble in analkali developing solution prior to exposure, but when acid is generatedfrom the component (B) upon exposure, the action of this acid causes anincrease in the polarity of the base component, thereby increasing thesolubility of the component (A1) in an alkali developing solution.Therefore, in the formation of a resist pattern, by conducting selectiveexposure of a resist film formed by applying the resist composition to asubstrate, the exposed portions of the resist film change from aninsoluble state to a soluble state in an alkali developing solution,whereas the unexposed portions of the resist film remain insoluble in analkali developing solution, and hence, a positive resist pattern isformed by alkali developing.

On the other hand, in the case of a solvent developing process, the basecomponent containing the component (A1) exhibits high solubility in anorganic developing solution prior to exposure, and when acid isgenerated from the component (B) upon exposure, the polarity of thecomponent (A1) is increased by the action of the generated acid, therebydecreasing the solubility of the component (A1) in an organic developingsolution. Therefore, in the formation of a resist pattern, by conductingselective exposure of a resist film formed by applying the resistcomposition to a substrate, the exposed portions of the resist filmchanges from an soluble state to an insoluble state in an organicdeveloping solution, whereas the unexposed portions of the resist filmremain soluble in an organic developing solution. As a result, byconducting development using an organic developing solution, a contrastcan be made between the exposed portions and unexposed portions, therebyforming a negative resist pattern.

In the resist composition of the present embodiment, as the component(A), one kind of compound may be used, or two or more kinds of compoundsmay be used in combination.

Component (A1)

The component (A1) is a resin component which exhibits changedsolubility in a developing solution under action of acid, and includes apolymer (hereafter, sometimes referred to as “component (A1-1)”) havinga structural unit (a0) in which a compound represented by generalformula (a0-1) has a polymerizable group within the W¹ portion convertedinto a main chain.

If desired, the component (A1-1) may include, in addition to thestructural unit (a0), other structural unit.

«Structural Unit (a0)»

The structural unit (a0) is a structural unit in which a compoundrepresented by general formula (a0-1) has a polymerizable group withinthe W¹ portion converted into a main chain.

The “polymerizable group” in the W¹ portion is a group that allows acompound having a polymerizable group to be polymerized by radicalpolymerization or the like, for example, a group containing acarbon-carbon multiple bond such as an ethylenic double bond.

“A polymerizable group has been converted to a main chain” means thatthe multiple bond within the polymerizable group has been cleaved toform a main chain. For example, in the case of a monomer having anethylenic double bond, the ethylenic double bond is cleaved such thatthe carbon-carbon single bond forms a main chain.

In formula (a0-1), W¹ represents a polymerizable group-containing group;C^(t) represents a tertiary carbon atom, and the α-position of C^(t) isa carbon atom which constitutes a carbon-carbon unsaturated bond; R¹¹represents an aromatic hydrocarbon group which may have a substituent,or a chain hydrocarbon group; R¹² and R¹³ are mutually bonded to form a5-membered aliphatic monocyclic group optionally having a substituent,or a condensed polycyclic hydrocarbon group containing a 5-memberedaliphatic monocyclic ring, the condensed polycyclic hydrocarbon groupoptionally having a substituent.

In general formula (a0-1), W¹ represents a polymerizablegroup-containing group.

Examples of the polymerizable group for the W¹ portion include a vinylgroup, an allyl group, an acryloyl group, a methacryloyl group, afluorovinyl group, a difluorovinyl group, a trifluorovinyl group, adifluorotrifluoromethylvinyl group, a trifluoroallyl group, aperfluoroallyl group, a trifluoromethylacryloyl group, anonylfluorobutylacryloyl group, a vinyl ether group, afluorine-containing vinyl ether group, an allyl ether group, anfluorine-containing allyl ether group, a styryl group, a vinylnaphthylgroup, a fluorine-containing styryl group, a fluorine-containingvinylnaphthyl group, a norbomyl group, a fluorine-containing norbomylgroup, and a silyl group.

The polymerizable group-containing group may be a group constituted ofonly a polymerizable group, or a group constituted of a polymerizablegroup and a group other than a polymerizable group. Examples of thegroup other than a polymerizable group include a divalent hydrocarbongroup which may have a substituent, and a divalent linking groupcontaining a hetero atom.

Preferable examples of W¹ include a group represented by the chemicalformula: C(R^(X11))(R^(X12))═C(R^(X13))—Ya^(x0)-.

In the chemical formula, R^(X11), R^(X12) and R^(X13) independentlyrepresents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms ora halogenated alkyl group having 1 to 5 carbon atoms, and Ya^(x0)represents a single bond or a divalent linking group.

In the chemical formula, as the alkyl group of 1 to 5 carbon atoms forR^(X11), R^(X12) and R^(X13), a linear or branched alkyl group of 1 to 5carbon atoms is preferable, and specific examples thereof include amethyl group, an ethyl group, a propyl group, an isopropyl group, ann-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, anisopentyl group and a neopentyl group. The halogenated alkyl group of 1to 5 carbon atoms represented by R is a group in which part or all ofthe hydrogen atoms of the aforementioned alkyl group of 1 to 5 carbonatoms have been substituted with halogen atoms. Examples of the halogenatom include a fluorine atom, a chlorine atom, a bromine atom and aniodine atom, and a fluorine atom is particularly desirable.

Among these examples, as R^(X11) and R^(X12) a hydrogen atom, an alkylgroup of 1 to 5 carbon atoms or a fluorinated alkyl group of 1 to 5carbon atoms is preferable, and in terms of industrial availability, ahydrogen atom or a methyl group is more preferable, and a hydrogen atomis still more preferable.

As R^(X13), a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or afluorinated alkyl group of 1 to 5 carbon atoms is preferable, and interms of industrial availability, a hydrogen atom or a methyl group ismore preferable.

In the aforementioned chemical formula, the divalent linking group forYa^(x0) is not particularly limited, and preferable examples thereofinclude a divalent hydrocarbon group which may have a substituent and adivalent linking group containing a hetero atom.

Divalent Hydrocarbon Group which May have a Substituent:

In the case where Ya^(x0) is a divalent linking group which may have asubstituent, the hydrocarbon group may be either an aliphatichydrocarbon group or an aromatic hydrocarbon group.

Aliphatic Hydrocarbon Group for Ya^(x0)

The “aliphatic hydrocarbon group” refers to a hydrocarbon group that hasno aromaticity. The aliphatic hydrocarbon group may be saturated orunsaturated. In general, the aliphatic hydrocarbon group is preferablysaturated.

Examples of the aliphatic hydrocarbon group include a linear or branchedaliphatic hydrocarbon group, and an aliphatic hydrocarbon groupcontaining a ring in the structure thereof can be given.

Linear or Branched Aliphatic Hydrocarbon Group

The linear aliphatic hydrocarbon group preferably has 1 to 10 carbonatoms, more preferably 1 to 6, still more preferably 1 to 4, and mostpreferably 1 to 3.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable. Specific examples thereof include a methylene group [—CH₂—],an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], atetramethylene group [—(CH₂)₄—] and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group preferably has 2 to 10 carbonatoms, more preferably 3 to 6, still more preferably 3 or 4, and mostpreferably 3.

As the branched aliphatic hydrocarbon group, branched alkylene groupsare preferred, and specific examples include various alkylalkylenegroups, including alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—,—C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—;alkylethylene groups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—,—C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylenegroups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; andalkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and—CH₂CH(CH₃)CH₂CH₂—. As the alkyl group within the alkylalkylene group, alinear alkyl group of 1 to 5 carbon atoms is preferable.

The linear or branched aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include a fluorine atom, afluorinated alkyl group of 1 to 5 carbon atoms, and a carbonyl group.

Aliphatic Hydrocarbon Group Containing a Ring in the Structure Thereof

As examples of the hydrocarbon group containing a ring in the structurethereof, a cyclic aliphatic hydrocarbon group containing a hetero atomin the ring structure thereof and may have a substituent (a group inwhich two hydrogen atoms have been removed from an aliphatic hydrocarbonring), a group in which the cyclic aliphatic hydrocarbon group is bondedto the terminal of the aforementioned chain-like aliphatic hydrocarbongroup, and a group in which the cyclic aliphatic group is interposedwithin the aforementioned linear or branched aliphatic hydrocarbongroup, can be given. As the linear or branched aliphatic hydrocarbongroup, the same groups as those described above can be used.

The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbonatoms, and more preferably 3 to 12 carbon atoms.

The cyclic aliphatic hydrocarbon group may be either a polycyclic groupor a monocyclic group. As the monocyclic aliphatic hydrocarbon group, agroup in which 2 hydrogen atoms have been removed from a monocycloalkaneis preferable. The monocycloalkane preferably has 3 to 6 carbon atoms,and specific examples thereof include cyclopentane and cyclohexane. Asthe polycyclic group, a group in which 2 hydrogen atoms have beenremoved from a polycycloalkane is preferable, and the polycyclic grouppreferably has 7 to 12 carbon atoms. Examples of the polycycloalkaneinclude adamantane, norbornane, isobornane, tricyclodecane andtetracyclododecane.

The cyclic aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include an alkyl group, analkoxy group, a halogen atom, a halogenated alkyl group, a hydroxylgroup and a carbonyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, ethoxy group,n-propoxy group, iso-propoxy group, n-butoxy group or tert-butoxy group,and most preferably a methoxy group or an ethoxy group.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

Examples of the halogenated alkyl group for the substituent includegroups in which part or all of the hydrogen atoms within theaforementioned alkyl groups has been substituted with the aforementionedhalogen atoms.

The cyclic aliphatic hydrocarbon group may have part of the carbon atomsconstituting the ring structure thereof substituted with a substituentcontaining a hetero atom. As the substituent containing a hetero atom,—O—, —C(═O)—O—, —S—, —S(═O)₂— or —S(═O)₂—O— is preferable.

Aromatic Hydrocarbon Group for Ya^(x0)

The aromatic hydrocarbon group is a hydrocarbon group having at leastone aromatic ring.

The aromatic ring is not particularly limited, as long as it is a cyclicconjugated compound having (4n+2)π electrons, and may be eithermonocyclic or polycyclic. The aromatic ring preferably has 5 to 30carbon atoms, more preferably 5 to 20 carbon atoms, and still morepreferably 6 to 15 carbon atoms, and most preferably 6 to 12 carbonatoms. Here, the number of carbon atoms within a substituent(s) is notincluded in the number of carbon atoms of the aromatic hydrocarbongroup. Examples of the aromatic ring include aromatic hydrocarbon rings,such as benzene, naphthalene, anthracene and phenanthrene; and aromatichetero rings in which part of the carbon atoms constituting theaforementioned aromatic hydrocarbon rings has been substituted with ahetero atom. Examples of the hetero atom within the aromatic heterorings include an oxygen atom, a sulfur atom and a nitrogen atom.Specific examples of the aromatic hetero ring include a pyridine ringand a thiophene ring.

Specific examples of the aromatic hydrocarbon group include a group inwhich two hydrogen atoms have been removed from the aforementionedaromatic hydrocarbon ring or aromatic hetero ring (arylene group orheteroarylene group); a group in which two hydrogen atoms have beenremoved from an aromatic compound having two or more aromatic rings(biphenyl, fluorene or the like); and a group in which one hydrogen atomof the aforementioned aromatic hydrocarbon ring or aromatic hetero ringhas been substituted with an alkylene group (a group in which onehydrogen atom has been removed from the aryl group within theaforementioned arylalkyl group such as a benzyl group, a phenethylgroup, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a1-naphthylethyl group, or a 2-naphthylethyl group, or a heteroarylalkylgroup). The alkylene group which is bonded to the aforementioned arylgroup or heteroaryl group preferably has 1 to 4 carbon atoms, morepreferably 1 or 2 carbon atoms, and most preferably 1 carbon atom.

With respect to the aromatic hydrocarbon group, the hydrogen atom withinthe aromatic hydrocarbon group may be substituted with a substituent.For example, the hydrogen atom bonded to the aromatic ring within thearomatic hydrocarbon group may be substituted with a substituent.Examples of substituents include an alkyl group, an alkoxy group, ahalogen atom, a halogenated alkyl group, and a hydroxyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

As the alkoxy group, the halogen atom and the halogenated alkyl groupfor the substituent, the same groups as the aforementioned substituentgroups for substituting a hydrogen atom within the cyclic aliphatichydrocarbon group can be used.

Divalent Linking Group Containing a Hetero Atom

In the case where Ya^(x) represents a divalent linking group containinga hetero atom, preferable examples of the linking group include —O—,—C(═O)—O—, —C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —NH—, —NH—C(═NH)— (may besubstituted with a substituent such as an alkyl group, an acyl group orthe like), —S—, —S(═O)₂—, —S(═O)₂—O—, and a group represented by generalformula: —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—,—[Y²¹—C(═O)—O]_(m′)—Y²²—, —Y²¹—O—C(═O)—Y²²— or —Y²¹—S(═O)₂—O—Y²²— [inthe formulae, Y²¹ and Y²² each independently represents a divalenthydrocarbon group which may have a substituent, O represents an oxygenatom, and m′ represents an integer of 0 to 3].

In the case where the divalent linking group containing a hetero atom is—C(═O)—NH—, —C(═O)—NH—C(═O)—, —NH— or —NH—C(═NH)—, H may be substitutedwith a substituent such as an alkyl group, an acyl group or the like.The substituent (an alkyl group, an acyl group or the like) preferablyhas 1 to 10 carbon atoms, more preferably 1 to 8, and most preferably 1to 5.

In general formulae —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—,—[Y²¹—C(═O)—O]_(m″)—Y²²—, —Y²¹—O—C(═O)—Y²²— or —Y²¹—S(═O)₂—O—Y²²—, Y²¹and Y²² each independently represents a divalent hydrocarbon group whichmay have a substituent. Examples of the divalent hydrocarbon groupinclude the same groups as those described above as the “divalenthydrocarbon group which may have a substituent” in the explanation ofthe aforementioned divalent linking group.

As Y²¹, a linear aliphatic hydrocarbon group is preferable, morepreferably a linear alkylene group, still more preferably a linearalkylene group of 1 to 5 carbon atoms, and a methylene group or anethylene group is particularly desirable.

As Y²², a linear or branched aliphatic hydrocarbon group is preferable,and a methylene group, an ethylene group or an alkylmethylene group ismore preferable. The alkyl group within the alkylmethylene group ispreferably a linear alkyl group of 1 to 5 carbon atoms, more preferablya linear alkyl group of 1 to 3 carbon atoms, and most preferably amethyl group.

In the group represented by the formula —[Y²¹—C(═O)—O]_(m)″—Y²²—, m″represents an integer of 0 to 3, preferably an integer of 0 to 2, morepreferably 0 or 1, and most preferably 1. Namely, it is particularlydesirable that the group represented by the formula—[Y²¹—C(═O)—O]_(m)″—Y²²— is a group represented by the formula—Y²¹—C(═O)—O—Y²²—. Among these, a group represented by the formula—(CH₂)_(a′)—C(═O)—O—(CH₂)_(b′)— is preferable. In the formula, a′ is aninteger of 1 to 10, preferably an integer of 1 to 8, more preferably aninteger of 1 to 5, still more preferably 1 or 2, and most preferably 1.b′ is an integer of 1 to 10, preferably an integer of 1 to 8, morepreferably an integer of 1 to 5, still more preferably 1 or 2, and mostpreferably 1.

Among these examples, as Ya^(x0), an ester bond [—C(═O)—O—, —O—C(═O)—],an ether bond (—O—), a linear or branched alkylene group, an aromatichydrocarbon group, or a combination thereof, or a single bond ispreferable. Among these, as Ya^(x0), an ester bond [—C(═O)—O—,—O—C(═O)—], a linear or branched alkylene group, or a combinationthereof, or a single bond is more preferable, and a single bond is mostpreferable.

In formula (a0-1), C^(t) represents a tertiary carbon atom, and theα-position of C^(t) is a carbon atom which constitutes a carbon-carbonunsaturated bond.

The “α-position of C^(t)” refers to the first carbon atom adjacent tothe carbon atom (C^(t)) bonded to the oxy group (—O—) in formula (a0-1).

In formula (a0-1), “—C^(t)(R¹¹)(R¹²)(R¹³)” is an acid dissociable group.The acid dissociable group protects the oxy group (—O—) side of thecarbonyloxy group [—C(═O)—O—] in formula (a0-1). An “acid dissociablegroup” exhibits acid dissociability such that the bond between the aciddissociable group and the adjacent oxygen atom (O) is cleaved by theaction of acid. When the acid dissociable group is dissociated by theaction of acid, a polar group which exhibits a higher polarity than theacid dissociable group is generated, and the polarity is increased. As aresult, the polarity of the entire component (A1) is increased. By theincrease in the polarity, the solubility in an alkali developingsolution changes, and the solubility in an alkali developing solution isrelatively increased, whereas the solubility in an organic developingsolution is relatively decreased.

In formula (a0-1), at least one of R¹¹, R¹² and R¹³ has a carbon atomconstituting a carbon-carbon unsaturated bond at the α-position ofC^(t).

In formula (a0-1), R¹¹ represents an aromatic hydrocarbon group whichmay have a substituent, or a chain hydrocarbon group.

Examples of the aromatic hydrocarbon group for R¹¹ include a group inwhich 1 or more hydrogen atoms have been removed from an aromatichydrocarbon ring having 5 to 30 carbon atoms. Among these examples, asR¹¹, a group in which 1 hydrogen atom has been removed from an aromatichydrocarbon group of 6 to 15 carbon atoms is preferable, a group inwhich 1 hydrogen atom has been removed from benzene, naphthalene,anthracene or phenanthrene is more preferable, a group in which 1hydrogen atom has been removed from benzene, naphthalene or anthraceneis still more preferable, and a group in which 1 hydrogen atom has beenremoved from benzene is most preferable.

Examples of the substituent for R¹¹ include a methyl group, an ethylgroup, a propyl group, a hydroxyl group, a carboxyl group, a halogenatom (a fluorine atom, a chlorine atom, a bromine atom, or the like), analkoxy group (a methoxy group, an ethoxy group, a propoxy group, abutoxy group, or the like), and an alkyloxycarbonyl group.

The chain hydrocarbon group for R¹¹ may be a saturated hydrocarbon groupor an unsaturated hydrocarbon group, and may be linear or branched.

The linear saturated hydrocarbon group (alkyl group) for R¹¹ preferablyhas 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms, stillmore preferably 1 to 4 carbon atoms, and most preferably 1 or 2 carbonatoms. Specific examples include a methyl group, an ethyl group, ann-propyl group, an n-butyl group and an n-pentyl group. Among these, amethyl group, an ethyl group or an n-butyl group is preferable, and amethyl group or an ethyl group is more preferable.

The branched alkyl group for R¹¹ preferably has 3 to 10 carbon atoms,and more preferably 3 to 5 carbon atoms. Specific examples include anisopropyl group, an isobutyl group, a tert-butyl group, an isopentylgroup, a neopentyl group a 1,1-diethylpropyl group and a2,2-dimethylbutyl group. Among these, an isopropyl group is preferable.

Examples of the unsaturated hydrocarbon group for R¹¹ include an alkenylgroup.

The alkenyl group for R¹¹ preferably has 2 to 10 carbon atoms, morepreferably 2 to 5 carbon atoms, still more preferably 2 to 4 carbonatoms, and most preferably 3 carbon atoms. Examples of linear alkenylgroups include a vinyl group, a propenyl group (an allyl group) and abutynyl group. Examples of branched alkenyl groups include a1-methylvinyl group, a 2-methylvinyl group, a 1-methylpropenyl group anda 2-methylpropenyl group. Among these examples, as the chain-likealkenyl group, a linear alkenyl group is preferable, a vinyl group or apropenyl group is more preferable, and a vinyl group is most preferable.

In formula (a0-1), R¹² and R¹³ are mutually bonded to form a 5-memberedaliphatic monocyclic group optionally having a substituent, or acondensed polycyclic hydrocarbon group containing a 5-membered aliphaticmonocyclic ring, the condensed polycyclic hydrocarbon group optionallyhaving a substituent.

Examples of the ring structure of the aliphatic monocyclic ring of the5-membered aliphatic monocyclic group include cyclopentane andcyclopentene.

Examples of the ring structure of the condensed polycyclic ring of thecondensed polycyclic hydrocarbon group include a condensed ring of a5-membered alicyclic hydrocarbon and an aromatic hydrocarbon. Thecondensed polycyclic ring may have a hetero atom. Examples of the heteroatom include an oxygen atom, a sulfur atom and a nitrogen atom. Examplesof the ring structure of the 5-membered alicyclic hydrocarbon portioninclude cyclopentane and cyclopentene. Examples of the ring structure ofthe aromatic hydrocarbon portion include benzene.

Examples of the substituent for the ring structure include —R^(P1),—R^(P2)—O—R^(P1), —R^(P2)—CO—R^(P1), —R^(P2)—CO—OR^(P1),—R^(P2)—O—CO—R^(P1), —R^(P2)—OH, —R^(P2)—CN or —R^(P2)—COOH (hereafter,these substituents are sometimes collectively referred to as “Ra⁰⁵”) ora divalent group which substitutes 2 hydrogen atoms of a methylene group(—CH₂—) (e.g., a methylidene group (═CH₂), an ethylidene group, or thelike).

Here, R^(P1) is a monovalent chain saturated hydrocarbon group having 1to 10 carbon atoms, a monovalent aliphatic cyclic saturated hydrocarbongroup having 3 to 20 carbon atoms, or a monovalent aromatic hydrocarbongroup having 6 to 30 carbon atoms.

R^(P2) represents a single bond, monovalent saturated chain hydrocarbongroup of 1 to 10 carbon atoms, a monovalent saturated aliphatic cyclichydrocarbon group of 3 to 20 carbon atoms or a monovalent aromatichydrocarbon group of 6 to 30 carbon atoms. However, the saturated chainhydrocarbon group, the saturated cyclic aliphatic hydrocarbon group andthe aromatic hydrocarbon group for R^(P1) and R^(P2) may have part orall of the hydrogen atoms substituted with fluorine. The aliphaticcyclic hydrocarbon group may have 1 or more substituents of 1 kind, or 1or more substituents of a plurality of kinds.

Examples of the monovalent chain saturated hydrocarbon group having 1 to10 carbon atoms include a methyl group, an ethyl group, a propyl group,a butyl group, a pentyl group, a hexyl group, a heptyl group, an octylgroup, and a decyl group. Examples of the monovalent aliphatic cyclicsaturated hydrocarbon group having 3 to 20 carbon atoms include amonocyclic aliphatic saturated hydrocarbon group such as a cyclopropylgroup, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, acycloheptyl group, a cyclooctyl group, a cyclodecyl group, and acyclododecyl group; and a polycyclic aliphatic saturated hydrocarbongroup such as a bicyclo[2.2.2]octanyl group, atricyclo[5.2.1.02,6]decanyl group, a tricyclo[3.3.1.13,7]decanyl group,a tetracyclo[6.2.1.13,6.02,7]dodecanyl group, and an adamantyl group.Examples of the monovalent aromatic hydrocarbon group having 6 to 30carbon atoms include a group obtained by removing one hydrogen atom fromthe aromatic hydrocarbon ring such as benzene, biphenyl, fluorene,naphthalene, anthracene, and phenanthrene. Examples of the divalentsaturated hydrocarbon group having 1 to 10 carbon atoms include a groupin which 1 hydrogen atom has been removed from the aforementionedmonovalent saturated hydrocarbon group having 1 to 10 carbon atoms.Examples of the divalent saturated aliphatic cyclic hydrocarbon grouphaving 3 to 20 carbon atoms include a group in which 1 hydrogen atom hasbeen removed from the aforementioned monovalent saturated aliphaticcyclic hydrocarbon group having 3 to 20 carbon atoms. Examples of thedivalent aromatic hydrocarbon group having 6 to 30 carbon atoms includea group in which 1 hydrogen atom has been removed from theaforementioned monovalent aromatic hydrocarbon group having 6 to 30carbon atoms.

In formula (a0-1), preferable examples of the acid dissociable grouprepresented by “—C^(t)(R¹¹)(R¹²)(R¹³)” include a group represented bygeneral formula (a0-r-1) shown below, a group represented by generalformula (a0-r-2) shown below, and a group represented by general formula(a0-r-3) shown below.

In formula (a0-r-1), Ra′¹¹⁰ represents a linear or branched alkyl grouphaving 1 to 12 carbon atoms optionally having part thereof substitutedwith a halogen atom or a hetero atom-containing group; Ra′¹¹¹ representsa group which forms a 5-membered aliphatic monocyclic group togetherwith the carbon atom to which Ra′¹¹⁰ is bonded, or a group which forms acondensed polycyclic hydrocarbon group containing a 5-membered aliphaticmonocyclic ring together with the carbon atom to which Ra′¹¹⁰ is bonded;provided that part or all of the hydrogen atoms of the 5-memberedaliphatic monocyclic group or the condensed polycyclic hydrocarbon groupmay be substituted.

In formula (a0-r-2), C^(t) represents a tertiary carbon atoms; Xarepresents a group which forms a 5-membered aliphatic monocyclic grouptogether with C^(t); provided that part or all of the hydrogen atoms ofthe 5-membered monocyclic aliphatic hydrocarbon group may besubstituted; Ra⁰¹ to Ra⁰³ each independently represents a hydrogen atom,a monovalent saturated chain hydrocarbon group of 1 to 10 carbon atomsor a monovalent saturated aliphatic cyclic hydrocarbon group of 3 to 20carbon atoms; provided that part or all of the hydrogen atoms of thesaturated chain hydrocarbon or the saturated aliphatic cyclichydrocarbon may be substituted; 2 or more of Ra⁰¹ to Ra⁰³ may bemutually bonded to form an aliphatic cyclic structure, but does not forma bridged structure.

In formula (a0-r-3), C^(t) represents a tertiary carbon atoms; Xaarepresents a group which forms a 5-membered aliphatic monocyclic grouptogether with C^(t); provided that part or all of the hydrogen atoms ofthe 5-membered monocyclic aliphatic hydrocarbon group may besubstituted; Ra⁰⁴ represents an aromatic hydrocarbon group which mayhave a substituent; * represents a bonding site.

In formula (a0-r-1), Ra′¹¹⁰ represents a linear or branched alkyl grouphaving 1 to 12 carbon atoms optionally having part thereof substitutedwith a halogen atom or a hetero atom-containing group.

The linear alkyl group for Ra′¹¹⁰ has 1 to 12 carbon atoms, preferably 1to 10 carbon atoms, and more preferably 1 to 5 carbon atoms. Specificexamples include a methyl group, an ethyl group, an n-propyl group, ann-butyl group and an n-pentyl group. Among these, a methyl group, anethyl group or an n-butyl group is preferable, and a methyl group or anethyl group is more preferable.

The branched alkyl group for Ra′¹¹⁰ preferably has 3 to 10 carbon atoms,and more preferably 3 to 6 carbon atoms. Specific examples include anisopropyl group, an isobutyl group, a tert-butyl group, an isopentylgroup, a neopentyl group, a 1,1-diethylpropyl group, a 1,1-dimethylbutylgroup, a 1,1-dimethylpentyl group and a 2,2-dimethylbutyl group. Amongthese examples, an isopropyl group or a tert-butyl group is preferable.

The alkyl group for Ra′¹¹⁰ may have part thereof substituted with ahalogen atom or a hetero atom-containing group. For example, part of thehydrogen atoms constituting the alkyl group may be substituted with ahalogen atom or a hetero atom-containing group. Further, for example,part of the carbon atoms constituting the alkyl group (e.g., a methylenegroup) may be substituted with a hetero atom-containing group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom. Examples of the hetero atom include anoxygen atom, a sulfur atom and a nitrogen atom. Examples of the heteroatom-containing group include an oxygen atom (—O—), —C(═O)—O—,—O—C(═O)—, —C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —NH—, —S—, —S(═O)₂— and—S(═O)₂—O—.

In formula (a0-r-1), examples of Ra′¹¹¹ (5-membered aliphatic monocyclicgroup formed together with the carbon atom to which Ra′¹¹⁰ is bonded)include cyclopentene, or cyclopentane having a divalent group (amethylidene group (═CH₂), an ethylidene group or the like) whichsubstitutes 2 hydrogen atoms of a methylene group (—CH₂—) bonded at theα-position of C^(t).

Examples of Ra′¹¹¹ (condensed polycyclic hydrocarbon group having a5-membered aliphatic monocyclic ring formed together with Ra′¹¹⁰)include a condensed ring of a 5-membered alicyclic hydrocarbon and anaromatic hydrocarbon, optionally having a hetero atom. Examples of thehetero atom contained in the condensed ring include an oxygen atom, asulfur atom and a nitrogen atom. Examples of the ring structure of the5-membered alicyclic hydrocarbon portion include cyclopentane andcyclopentene. Examples of the ring structure of the aromatic hydrocarbonportion include benzene.

In formula (a0-r-2), C^(t) represents a tertiary carbon atoms.

In formula (a0-r-2), Xa represents a group which forms a 5-memberedaliphatic monocyclic group together with C^(t), provided that part orall of the hydrogen atoms of the 5-membered monocyclic aliphatichydrocarbon group may be substituted;

Examples of the ring structure of the aliphatic monocyclic ring of the5-membered monocyclic aliphatic hydrocarbon group formed by Xa and C^(t)include cyclopentane. Examples of the substituent for the ring structureinclude the same groups as those described above for Ra⁰⁵.

In formula (a0-r-2), Ra⁰¹ to Ra⁰³ each independently represents ahydrogen atom, a monovalent saturated chain hydrocarbon group of 1 to 10carbon atoms or a monovalent saturated aliphatic cyclic hydrocarbongroup of 3 to 20 carbon atoms, provided that part or all of the hydrogenatoms of the saturated chain hydrocarbon or the saturated aliphaticcyclic hydrocarbon may be substituted; 2 or more of Ra⁰¹ to Ra⁰³ may bemutually bonded to form an aliphatic cyclic structure, but does not forma bridged structure.

In formula (a0-r-2), examples of the monovalent saturated chainhydrocarbon group of 1 to 10 carbon atoms for Ra⁰¹ to Ra⁰³ include amethyl group, an ethyl group, a propyl group, a butyl group, a pentylgroup, a hexyl group, a heptyl group, an octyl group, and a decyl group.

Examples of the monovalent aliphatic cyclic saturated hydrocarbon grouphaving 3 to 20 carbon atoms for Ra⁰¹ to Ra⁰³ include a monocyclicaliphatic saturated hydrocarbon group such as a cyclopropyl group, acyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, a cyclooctyl group, a cyclodecyl group, and a cyclododecyl group;and a polycyclic aliphatic saturated hydrocarbon group such as abicyclo[2.2.2]octanyl group, a tricyclo[5.2.1.02,6]decanyl group, atricyclo[3.3.1.13,7]decanyl group, atetracyclo[6.2.1.13,6.02,7]dodecanyl group, and an adamantyl group.

Among these examples, in terms of ease in synthesis of the compound(a0-1), Ra⁰¹ to Ra⁰³ is preferably a hydrogen atom or a monovalentsaturated hydrocarbon group having 1 to 10 carbon atoms, more preferablya hydrogen atom, a methyl group or an ethyl group, and most preferably ahydrogen atom.

As the substituent for the saturated chain hydrocarbon group orsaturated cyclic aliphatic hydrocarbon group represented by Ra⁰¹ toRa⁰³, for example, the same substituents as those described above forRa⁰⁵ may be mentioned.

Examples of the group containing a carbon-carbon double bond which isgenerated by forming a cyclic structure in which two or more of Ra⁰¹ toRa⁰³ are bonded to each other include a cyclopentenyl group, acyclohexenyl group, a methyl cyclopentenyl group, a methyl cyclohexenylgroup, a cyclopentylideneethenyl group, and a cyclohexylidenethenylgroup. Among these examples, in terms of ease in synthesis of thecompound (a0-1), a cyclopentenyl group, a cyclohexenyl group or acyclopentylideneethenyl group is preferable.

In formula (a0-r-3), C^(t) represents a tertiary carbon atoms.

In formula (a0-r-3), Xaa represents a group which forms a 5-memberedaliphatic monocyclic group together with C^(t). provided that part orall of the hydrogen atoms of the 5-membered monocyclic aliphatichydrocarbon group may be substituted;

Examples of the ring structure of the aliphatic monocyclic ring of the5-membered monocyclic aliphatic hydrocarbon group formed by Xaa andC^(t) include cyclopentane. Examples of the substituent for the ringstructure include the same groups as those described above for Ra⁰⁵.

In formula (a0-r-3), Ra⁰⁴ represents an aromatic hydrocarbon group whichmay have a substituent. Examples of the aromatic hydrocarbon group forRa⁰⁴ include the same aromatic hydrocarbon groups as those for R¹¹.Among these examples, as Ra⁰⁴, a group in which 1 or more hydrogen atomshave been removed from an aromatic hydrocarbon ring having 6 to 15carbon atoms is preferable, and a group in which 1 or more hydrogenatoms have been removed from benzene is more preferable.

As the substituent for Ra⁰⁴, the same substituents as those describedabove for the aromatic hydrocarbon group represented by R¹¹ may bementioned.

Specific examples of the group represented by the aforementioned formula(a0-r-1) are shown below. * indicates the bonding site with the oxygroup (—O—).

Specific examples of the group represented by the aforementioned formula(a0-r-2) are shown below. * indicates the bonding site with the oxygroup (—O—).

Specific examples of the group represented by the aforementioned formula(a0-r-3) are shown below. * indicates the bonding site with the oxygroup (—O—).

Specific examples of the structural unit (a0) are shown below. In theformulae shown below, R^(α) represents a hydrogen atom, a methyl groupor a trifluoromethyl group.

Among the above examples, as the structural unit (a0), at least onemember selected from the group consisting of structural unitsrepresented by chemical formulae (a0-u101) to (a0-u108), chemicalformulae (a0-u111) to (a0-u113), chemical formulae (a0-u121) to(a0-u124) and chemical formulae (a0-u131) is preferable.

As the structural unit (a0) contained in the component (A1-1), 1 kind ofstructural unit may be used, or 2 or more kinds may be used.

In the component (A1-1), the amount of the structural unit (a0) based onthe combined total (100 mol %) of all structural units constituting thecomponent (A1-1) is preferably 40 mol % or more, more preferably 40 to80 mol %, still more preferably 40 to 70 mol %, and most preferably 40to 60 mol %.

When the amount of the structural unit (a0) is at least as large as thelower limit of the above-mentioned preferable range, various lithographyproperties such as sensitivity, resolution and roughness may beimproved. On the other hand, when the amount of the structural unit (a0)is no more than the upper limit of the above-mentioned range, a goodbalance may be achieved with the other structural units, and thelithography properties may be improved.

«Other Structural Units»

If desired, the component (A1-1) may include, in addition to thestructural unit (a0), other structural unit.

Examples of the other structural unit include a structural unit (a0-2)in which a compound represented by general formula (a0-2) has apolymerizable group within the W² portion converted into a main chain; astructural unit (a1) containing an acid decomposable group that exhibitsincreased polarity by the action of acid; a structural unit (a2)containing a lactone-containing cyclic group, an —SO₂— containing cyclicgroup or a carbonate-containing cyclic group; a structural unit (a3)containing a polar group-containing aliphatic hydrocarbon group; astructural unit (a9) represented by general formula (a9-1); a structuralunit derived from styrene; a structural unit derived from a styrenederivative; and a structural unit containing an acid non-dissociablealiphatic cyclic group.

Structural Unit (a0-2):

The component (A1-1) may include, in addition to the structural unit(a0), a structural unit (a0-2) represented by general formula (a0-2)shown below.

In the formula, W² represents a polymerizable group-containing group;Wa^(x0) represents a (n_(ax0)+1)-valent cyclic group having aromaticityand optionally having a substituent; Wa^(x0) may form a condensed ringtogether with W²; and n_(ax0) represents an integer of 1 to 3.

In formula (a0-2), W² represents a polymerizable group-containing group.The polymerizable group-containing group for W² is the same as definedfor the polymerizable group-containing group for W¹ in theaforementioned formula (a0-1).

Preferable examples of W² include a group represented by theaforementioned chemical formula:C(R^(X11))(R^(X12))═C(R^(X13))—Ya^(x0)-.

In the chemical formula, R^(X11), R^(X12) and R^(X13) independentlyrepresents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms ora halogenated alkyl group having 1 to 5 carbon atoms, and Ya^(x0)represents a single bond or a divalent linking group.

Regarding W², as R^(X11) and R^(X12), a hydrogen atom, an alkyl group of1 to 5 carbon atoms or a fluorinated alkyl group of 1 to 5 carbon atomsis preferable, and in terms of industrial availability, a hydrogen atomor a methyl group is more preferable, and a hydrogen atom is still morepreferable.

Further, regarding W², as R^(X13), a hydrogen atom, an alkyl group of 1to 5 carbon atoms or a fluorinated alkyl group of 1 to 5 carbon atoms ispreferable, and in terms of industrial availability, a hydrogen atom ora methyl group is more preferable, and a hydrogen atom is still morepreferable.

Regarding W², as Ya^(x0), an ester bond [—C(═O)—O—, —O—C(═O)—], an etherbond (—O—), a linear or branched alkylene group, an aromatic hydrocarbongroup, or a combination thereof, or a single bond is preferable, anester bond [—C(═O)—O—, —O—C(═O)—], a linear or branched alkylene group,an aromatic hydrocarbon group, or a combination thereof, or a singlebond is more preferable, and an ester bond [—C(═O)—O—, —O—C(═O)—] or asingle bond is most preferable.

In formula (a0-2), Wa^(x0) represents a (n_(ax0)+1)-valent cyclic grouphaving aromaticity and optionally having a substituent.

Regarding Wa^(x0), examples of the cyclic group having aromaticityinclude a group in which (n_(ax0)+1) hydrogen atoms have been removedfrom an aromatic ring. The aromatic ring is not particularly limited, aslong as it is a cyclic conjugated compound having (4n+2)π electrons, andmay be either monocyclic or polycyclic. The aromatic ring preferably has5 to 30 carbon atoms, more preferably 5 to 20 carbon atoms, and stillmore preferably 6 to 15 carbon atoms, and most preferably 6 to 12 carbonatoms. Examples of the aromatic ring include aromatic hydrocarbon rings,such as benzene, naphthalene, anthracene and phenanthrene; and aromatichetero rings in which part of the carbon atoms constituting theaforementioned aromatic hydrocarbon rings has been substituted with ahetero atom. Examples of the hetero atom within the aromatic heterorings include an oxygen atom, a sulfur atom and a nitrogen atom.Specific examples of the aromatic hetero ring include a pyridine ringand a thiophene ring.

Examples of the substituent for Wa^(x0) a carboxy group, a halogen atom(such as a fluorine atom, a chlorine atom or a chlorine atom), an alkoxygroup (such as a methoxy group, an ethoxy group, a propoxy group or abutoxy group), and an alkyloxycarbonyl group.

In formula (a0-2), Wa^(x0) may form a condensed ring together with W².

In the case where W² forms a condensed ring together with Wa^(x0),examples of the cyclic structure include a condensed ring of analicyclic hydrocarbon and an aromatic hydrocarbon. The condensed ringformed by Wa^(x0) and W² may have a hetero atom.

Regarding the condensed ring formed by W² and Wa^(x0), the alicyclichydrocarbon portion may be monocyclic or polycyclic.

Examples of the condensed ring formed by W² and Wa^(x0) include acondensed ring formed by the polymerizable group of the W² portion andWa^(x0), and a condensed ring formed by a group other than thepolymerizable group of the W² portion and the Wa^(x0).

The condensed ring formed by W² and Wa^(x0) may have a substituent.Examples of the substituent include a methyl group, an ethyl group, apropyl group, a hydroxy group, a hydroxyalkyl group, a carboxy group, ahalogen atom (such as a fluorine atom, a chlorine atom or bromine atom),an alkoxy group (such as a methoxy group, an ethoxy group, a propoxygroup or a butoxy group), an acyl group, an alkyloxycarbonyl group, andan alkylcarbonyloxy group.

Specific examples of the condensed ring formed by W² and Wa^(x0) areshown below. W^(α) represents a polymerizable group.

** represents a bonding site with a hydroxy group.

In formula (a0-2), n_(ax0) represents an integer of 1 to 3, preferably 1or 2, and more preferably 1.

Preferable examples of the structural unit (a0-2) include a structuralunit represented by general formula (a0-2-u1) shown below.

In the formula, R^(X11), R^(X12) and R^(X13) each independentlyrepresents a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or ahalogenated alkyl group of 1 to 5 carbon atoms; Ya^(x1) represents asingle bond or a divalent linking group; Wa^(x1) represents a(n_(ax1)+1)-valent cyclic group having aromaticity and optionally havinga substituent; provided that Ya^(x1) and Wa^(x1) may together form acondensed ring, or R^(X11), Ya^(x1) and Wa^(x1) may together form acondensed ring; and n_(ax1) represents an integer of 1 to 3.

In formula (a0-2-u1), R^(X11), R^(X12) and R^(X13) each independentlyrepresents a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or ahalogenated alkyl group of 1 to 5 carbon atoms.

The alkyl group of 1 to 5 carbon atoms or the halogenated alkyl group of1 to 5 carbon atoms for R^(X11), R^(X12) and R^(X13) is the same asdescribed above.

In formula (a0-2-u1), as R^(X11) and R^(X12), a hydrogen atom, an alkylgroup of 1 to 5 carbon atoms or a fluorinated alkyl group of 1 to 5carbon atoms is preferable, and in terms of industrial availability, ahydrogen atom or a methyl group is more preferable, and a hydrogen atomis still more preferable.

In formula (a0-2-u1), as R^(X13), a hydrogen atom, an alkyl group of 1to 5 carbon atoms or a fluorinated alkyl group of 1 to 5 carbon atoms ispreferable, and in terms of industrial availability, a hydrogen atom ora methyl group is more preferable.

In formula (a0-2-u1), Ya^(x1) represents a single bond or a divalentlinking group.

Preferable examples of the divalent linking group for Ya^(x1) include adivalent hydrocarbon group which may have a substituent, and a divalentlinking group containing a hetero atom. As the divalent linking groupwhich may have a substituent or the divalent linking group containing ahetero atom for Ya^(x1), the same divalent linking groups (divalentlinking group which may have a substituent or divalent linking groupcontaining a hetero atom) described above for Ya^(x0) may be mentioned.

Among these examples, as Ya^(x1), an ester bond [—C(═O)—O—, —O—C(═O)—],an ether bond (—O—), —C(═O)—NH—, a linear or branched alkylene group, ora combination thereof, or a single bond is preferable, an ester bond[—C(═O)—O—, —O—C(═O)—], a linear or branched alkylene group, or acombination thereof, or a single bond is more preferable, and an esterbond [—C(═O)—O—, —O—C(═O)—] or a single bond is most preferable.

In formula (a0-2-u1), Wa^(x1) represents a (n_(ax1)+1)-valent cyclicgroup having aromaticity and optionally having a substituent.

The cyclic group having aromaticity for Wa^(x1) is the same as definedfor Wa^(x0) in the aforementioned formula (a0-2).

In formula (a0-2-u1), Ya^(x1) and Wa^(x1) may together form a condensedring, or R^(X11), Ya^(x1) and Wa^(x1) may together form a condensedring.

The condensed ring is the same as defined for the condensed ring formedby W² and Wa^(x0) (the condensed ring formed by the polymerizable groupof the W² portion and Wa^(x0), and the condensed ring formed by a groupother than the polymerizable group of the W² portion and Wa^(x0)).

Specific examples of the case where R^(X11), Ya^(x1) and Wa^(x1)together form a condensed ring in the aforementioned formula (a0-2-u1)are shown below. ** represents a bonding site with a hydroxy group.

Specific examples of the case where Ya^(x1) and Wa^(x1) together form acondensed ring in the aforementioned formula (a0-2-u1) are shownbelow. * indicates a bonding site where a carbon atom which constitutesthe main chain and is bonded to R^(X13) is bonded. ** represents abonding site with a hydroxy group.

In formula (a0-2-u1), n_(ax1) is an integer of 1 to 3, preferably 1 or2, and more preferably 1.

Specific examples of the structural unit (a0-2) are shown below. In thefollowing formulae, R^(α) represents a hydrogen atom, a methyl group ora trifluoromethyl group.

Among the above examples, as the structural unit (a0-2), at least onemember selected from the group consisting of structural unitsrepresented by chemical formulae (a0-2-u01) to (a0-2-u15), chemicalformulae (a0-2-u21) to (a0-2-u33) and chemical formulae (a0-2-u41) to(a0-2-u45) is preferable.

Among these examples, as the structural unit (a0-2), at least one memberselected from the group consisting of structural units represented byformulae (a0-2-u01) to (a0-2-u12) and chemical formulae (a0-2-u21) to(a0-2-u33) is more preferable.

As the structural unit (a0-2) contained in the component (A1-1), 1 kindof structural unit may be used, or 2 or more kinds may be used.

In the component (A1-1), the amount of the structural unit (a0-2) basedon the combined total (100 mol %) of all structural units constitutingthe component (A1-1) is, for example, 0 to 80 mol %, preferably 10 to 80mol %, more preferably 20 to 70 mol %, and still more preferably 30 to60 mol %.

When the amount of the structural unit (a0-2) is at least as large asthe lower limit of the above-mentioned preferable range, variouslithography properties such as sensitivity, resolution and roughness maybe improved. On the other hand, when the amount of the structural unit(a0-2) is no more than the upper limit of the above-mentioned range, agood balance may be achieved with the other structural units, and thelithography properties may be improved.

Structural Unit (a1):

In addition to the structural unit (a0), the component (A1-1) mayinclude a structural unit (a1) containing an acid decomposable groupthat exhibits increased polarity by the action of acid (provided thatstructural units which fall under the definition of the structural unit(a0) is excluded).

The term “acid decomposable group” refers to a group in which at least apart of the bond within the structure thereof is cleaved by the actionof an acid.

Examples of acid decomposable groups which exhibit increased polarity bythe action of an acid include groups which are decomposed by the actionof an acid to form a polar group.

Examples of the polar group include a carboxy group, a hydroxy group, anamino group and a sulfo group (—SO₃H). Among these, a polar groupcontaining —OH in the structure thereof (hereafter, referred to as“OH-containing polar group”) is preferable, a carboxy group or a hydroxygroup is more preferable, and a carboxy group is particularly desirable.

More specifically, as an example of an acid decomposable group, a groupin which the aforementioned polar group has been protected with an aciddissociable group (such as a group in which the hydrogen atom of theOH-containing polar group has been protected with an acid dissociablegroup) can be given.

The “acid dissociable group” refers to both (i) a group in which thebond between the acid dissociable group and the adjacent atom is cleavedby the action of acid; and (ii) a group in which one of the bonds iscleaved by the action of acid, and then a decarboxylation reactionoccurs, thereby cleaving the bond between the acid dissociable group andthe adjacent atom.

It is necessary that the acid dissociable group that constitutes theacid decomposable group is a group which exhibits a lower polarity thanthe polar group generated by the dissociation of the acid dissociablegroup. Thus, when the acid dissociable group is dissociated by theaction of acid, a polar group exhibiting a higher polarity than that ofthe acid dissociable group is generated, thereby increasing thepolarity. As a result, the polarity of the entire component (A1) isincreased. By the increase in the polarity, the solubility in an alkalideveloping solution changes, and the solubility in an alkali developingsolution is relatively increased, whereas the solubility in an organicdeveloping solution is relatively decreased.

Examples of the acid dissociable group for the structural unit (a1)include acid dissociable groups which have been proposed for a baseresin of a chemically amplified resist composition, provided that theacid dissociable group “—C^(t)(R¹¹)(R¹²)(R¹³)” in the aforementionedgeneral formula (a0-1) is excluded.

Specific examples of acid dissociable groups for the base resin of aconventional chemically amplified resist include “acetal-type aciddissociable group”, “tertiary alkyl ester-type acid dissociable group”and “tertiary alkyloxycarbonyl acid dissociable group” described below.

Acetal-Type Acid Dissociable Group

Examples of the acid dissociable group for protecting the carboxy groupor hydroxy group as a polar group include the acid dissociable grouprepresented by general formula (a1-r-1) shown below (hereafter, referredto as “acetal-type acid dissociable group”).

In the formula, Ra′¹ and Ra′² represents a hydrogen atom or an alkylgroup; and Ra′³ represents a hydrocarbon group, provided that Ra′³ maybe bonded to Ra′¹ or Ra′².

In the formula (a1-r-1), it is preferable that at least one of Ra′¹ andRa′² represents a hydrogen atom, and it is more preferable that both ofRa′¹ and Ra′² represent a hydrogen atom.

In the case where Ra′¹ or Ra′² is an alkyl group, as the alkyl group,the same alkyl groups as those described above the for the substituentwhich may be bonded to the carbon atom on the α-position of theaforementioned α-substituted acrylate ester can be mentioned, and analkyl group of 1 to 5 carbon atoms is preferable. Specific examplesinclude linear or branched alkyl groups. Specific examples of the alkylgroup include a methyl group, an ethyl group, a propyl group, anisopropyl group, an n-butyl group, an isobutyl group, a tert-butylgroup, a pentyl group, an isopentyl group and a neopentyl group. Ofthese, a methyl group or an ethyl group is preferable, and a methylgroup is particularly preferable.

In formula (a1-r-1), examples of the hydrocarbon group for Ra′³ includea linear or branched alkyl group and a cyclic hydrocarbon group.

The linear alkyl group preferably has 1 to 5 carbon atoms, morepreferably 1 to 4, and still more preferably 1 or 2. Specific examplesinclude a methyl group, an ethyl group, an n-propyl group, an n-butylgroup and an n-pentyl group. Among these, a methyl group, an ethyl groupor an n-butyl group is preferable, and a methyl group or an ethyl groupis more preferable.

The branched alkyl group preferably has 3 to 10 carbon atoms, and morepreferably 3 to 5. Specific examples include an isopropyl group, anisobutyl group, a tert-butyl group, an isopentyl group, a neopentylgroup a 1,1-diethylpropyl group and a 2,2-dimethylbutyl group. Amongthese, an isopropyl group is preferable.

In the case where Ra′³ represents a cyclic hydrocarbon group, the cyclichydrocarbon group may be an aliphatic hydrocarbon group or an aromatichydrocarbon group, and may be polycyclic or monocyclic.

As the monocyclic aliphatic hydrocarbon group, a group in which 1hydrogen atom has been removed from a monocycloalkane is preferable. Themonocycloalkane preferably has 3 to 6 carbon atoms, and specificexamples thereof include cyclopentane and cyclohexane.

As the polycyclic aliphatic hydrocarbon group, a group in which 1hydrogen atom has been removed from a polycycloalkane is preferable, andthe polycyclic group preferably has 7 to 12 carbon atoms. Examples ofthe polycycloalkane include adamantane, norbornane, isobornane,tricyclodecane and tetracyclododecane.

When the monovalent hydrocarbon group for Ra′³ is an aromatichydrocarbon group, the aromatic hydrocarbon group is a hydrocarbon grouphaving at least one aromatic ring.

The aromatic ring is not particularly limited, as long as it is a cyclicconjugated compound having (4n+2)π electrons, and may be eithermonocyclic or polycyclic. The aromatic ring preferably has 5 to 30carbon atoms, more preferably 5 to 20, still more preferably 6 to 15,and most preferably 6 to 12. Examples of the aromatic ring includearomatic hydrocarbon rings, such as benzene, naphthalene, anthracene andphenanthrene; and aromatic hetero rings in which part of the carbonatoms constituting the aforementioned aromatic hydrocarbon rings hasbeen substituted with a hetero atom. Examples of the hetero atom withinthe aromatic hetero rings include an oxygen atom, a sulfur atom and anitrogen atom. Specific examples of the aromatic hetero ring include apyridine ring and a thiophene ring.

Specific examples of the aromatic hydrocarbon group for Ra′³ include agroup in which one hydrogen atom has been removed from theaforementioned aromatic hydrocarbon ring or aromatic hetero ring (arylgroup or heteroaryl group); a group in which one hydrogen atom has beenremoved from an aromatic compound having two or more aromatic rings(biphenyl, fluorene or the like); and a group in which one hydrogen atomof the aforementioned aromatic hydrocarbon ring or aromatic hetero ringhas been substituted with an alkylene group (an arylalkyl group such asa benzyl group, a phenethyl group, a 1-naphthylmethyl group, a2-naphthylmethyl group, a 1-naphthylethyl group, or a 2-naphthylethylgroup). The alkylene group bonded to the aforementioned aromatichydrocarbon ring or the aromatic hetero ring preferably has 1 to 4carbon atoms, more preferably 1 or 2 carbon atoms, and most preferably 1carbon atom.

In the case where Ra′³ is bonded to Ra′¹ or Ra′² to form a ring, thecyclic group is preferably a 4 to 7-membered ring, and more preferably a4 to 6-membered ring. Specific examples of the cyclic group includetetrahydropyranyl group and tetrahydrofuranyl group.

Tertiary Alkyl Ester-Type Acid Dissociable Group

Examples of the acid dissociable group for protecting the carboxy groupas a polar group include the acid dissociable group represented bygeneral formula (a1-r-2) shown below. Among the acid dissociable groupsrepresented by general formula (a1-r-2), for convenience, a group whichis constituted of alkyl groups is referred to as “tertiary ester-typeacid dissociable group”.

In the formula, Ra′⁴ to Ra′⁶ each independently represents a hydrocarbongroup, provided that Ra′⁵ and Ra′⁶ may be mutually bonded to form aring.

As the hydrocarbon group for Ra′⁴ to Ra′⁶, the same groups as thosedescribed above for Ra′³ can be mentioned.

Ra′⁴ is preferably an alkyl group of 1 to 5 carbon atoms. In the casewhere Ra′⁵ and Ra′⁶ are mutually bonded to form a ring, a grouprepresented by general formula (a1-r2-1) shown below can be mentioned.On the other hand, in the case where Ra′⁴ to Ra′⁶ are not mutuallybonded and independently represent a hydrocarbon group, the grouprepresented by general formula (a1-r2-2) shown below can be mentioned.

In the formulae, Ra′¹⁰ represents an alkyl group of 1 to 10 carbonatoms; Ra′¹¹ is a group which forms an aliphatic cyclic group togetherwith a carbon atom having Ra′¹⁰ bonded thereto; and Ra′¹² to Ra′¹⁴ eachindependently represents a hydrocarbon group.

In the formula (a1-r2-1), as the alkyl group of 1 to 10 carbon atoms forRa′¹⁰ the same groups as described above for the linear or branchedalkyl group for Ra′³ in the formula (a1-r-1) are preferable. In theformula (a1-r2-1), as the aliphatic cyclic group which is formed byRa′¹¹ together with the carbon atom bonded to Ra′¹⁰, the same groups asthose described above for the monocyclic or polycyclic aliphatichydrocarbon group for Ra′³ in the formula (a1-r-1) are preferable.

In the formula (a1-r2-2), it is preferable that Ra′¹² and Ra′¹⁴ eachindependently represents an alkyl group or 1 to 10 carbon atoms, and itis more preferable that the alkyl group is the same group as thedescribed above for the linear or branched alkyl group for Ra′³ in theformula (a1-r-1), it is still more preferable that the alkyl group is alinear alkyl group of 1 to 5 carbon atoms, and it is particularlypreferable that the alkyl group is a methyl group or an ethyl group.

In the formula (a1-r2-2), it is preferable that Ra′¹³ is the same groupas described above for the linear or branched alkyl group or monocyclicor polycyclic alicyclic hydrocarbon group for Ra′³ in the formula(a1-r-1). Among these examples, monocyclic or polycyclic aliphatichydrocarbon group for Ra′³ are more preferable.

Specific examples of the group represented by the aforementioned formula(a1-r2-1) are shown below. * represents a bonding site.

Specific examples of the group represented by the aforementioned formula(a1-r2-2) are shown below.

Tertiary Alkyloxycarbonyl Acid Dissociable Group

Examples of the acid dissociable group for protecting a hydroxy group asa polar group include the acid dissociable group represented by generalformula (a1-r-3) shown below (hereafter, for convenience, referred to as“tertiary alkyloxycarbonyl-type acid dissociable group”).

In the formula, Ra′⁷ to Ra′⁹ each independently represents an alkylgroup.

In formula (a1-r-3), each of Ra′⁷ to Ra′⁹ is preferably an alkyl grouphaving 1 to 5 carbon atoms, and more preferably an alkyl group having 1to 3 carbon atoms.

Further, the total number of carbon atoms within the alkyl group ispreferably 3 to 7, more preferably 3 to 5, and most preferably 3 or 4.

Examples of the structural unit (a1) include a structural unit derivedfrom an acrylate ester which may have the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent; astructural unit derived from an acrylamide; a structural unit derivedfrom hydroxystyrene or a hydroxystyrene derivative in which at least apart of the hydrogen atom of the hydroxy group is protected with asubstituent containing an acid decomposable group; and a structural unitderived from vinylbenzoic acid or a vinylbenzoic acid derivative inwhich at least a part of the hydrogen atom within —C(═O)—OH is protectedwith a substituent containing an acid decomposable group.

As the structural unit (a1), a structural unit derived from an acrylateester which may have the hydrogen atom bonded to the carbon atom on theα-position substituted with a substituent is preferable.

Specific examples of preferable structural units for the structural unit(a1) include structural units represented by general formula (a1-1) or(a1-2) shown below.

In the formula, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms; Va¹represents a divalent hydrocarbon group optionally having an ether bond;n_(a1) represents an integer of 0 to 2; Ra¹ represents an aciddissociable group represented by the aforementioned formula (a1-r-1) or(a1-r-2); Wa¹ represents a hydrocarbon group having a valency ofn_(a2)+1; n_(a2) represents an integer of 1 to 3; Ra² represents an aciddissociable group represented by the aforementioned formula (a1-r-1) or(a1-r-3).

In the aforementioned formula (a1-1), as the alkyl group of 1 to 5carbon atoms for R, a linear or branched alkyl group of 1 to 5 carbonatoms is preferable, and specific examples thereof include a methylgroup, an ethyl group, a propyl group, an isopropyl group, an n-butylgroup, an isobutyl group, a tert-butyl group, a pentyl group, anisopentyl group and a neopentyl group. The halogenated alkyl group of 1to 5 carbon atoms represented by R is a group in which part or all ofthe hydrogen atoms of the aforementioned alkyl group of 1 to 5 carbonatoms have been substituted with halogen atoms. Examples of the halogenatom include a fluorine atom, a chlorine atom, a bromine atom and aniodine atom, and a fluorine atom is particularly desirable.

As R, a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or afluorinated alkyl group of 1 to 5 carbon atoms is preferable, and ahydrogen atom or a methyl group is particularly desirable in terms ofindustrial availability.

In formula (a1-1), the divalent linking group for Va¹ is the same asdefined for the divalent linking group for Ya^(x0) described above inrelation to W¹ in the aforementioned formula (a0-1).

In the aforementioned formula (a1-2), the hydrocarbon group for Wa¹having a valency of n_(a2)+1 may be either an aliphatic hydrocarbongroup or an aromatic hydrocarbon group. The aliphatic cyclic grouprefers to a hydrocarbon group that has no aromaticity, and may be eithersaturated or unsaturated, but is preferably saturated. Examples of thealiphatic hydrocarbon group include a linear or branched aliphatichydrocarbon group, an aliphatic hydrocarbon group containing a ring inthe structure thereof, and a combination of the linear or branchedaliphatic hydrocarbon group and the aliphatic hydrocarbon groupcontaining a ring in the structure thereof.

The valency of n_(a2)+1 is preferably divalent, trivalent ortetravalent, and divalent or trivalent is more preferable.

Specific examples of structural unit represented by formula (a1-1) areshown below. In the formulae shown below, R^(α) represents a hydrogenatom, a methyl group or a trifluoromethyl group.

Specific examples of structural unit represented by formula (a1-2) areshown below.

As the structural unit (a1) contained in the component (A1-1), 1 kind ofstructural unit may be used, or 2 or more kinds of structural units maybe used.

When the component (A1-1) includes the structural unit (a1), the amountof the structural unit (a1) based on the combined total of allstructural units constituting the component (A1-1) (100 mol %) ispreferably 1 to 50 mol %, more preferably 5 to 45 mol %, and still morepreferably 5 to 30 mol %.

When the amount of the structural unit (a1) is at least as large as thelower limit of the above-mentioned range, a resist pattern can bereliably obtained, and the sensitivity, resolution, roughness andvarious lithography properties such as EL margin are further improved.On the other hand, when the amount of the structural unit (a1) is nomore than the upper limit of the above-mentioned range, a good balancecan be achieved with the other structural units.

Structural Unit (a2):

The component (A1-1) may include, in addition to the structural unit(a0), a structural unit (a2) containing a lactone-containing cyclicgroup, an —SO₂— containing cyclic group or a carbonate-containing cyclicgroup (provided that structural units which fall under the definition ofthe structural unit (a0) or the structural unit (a1) are excluded).

When the component (A1-1) is used for forming a resist film, thelactone-containing cyclic group, the —SO₂— containing cyclic group orthe carbonate-containing cyclic group within the structural unit (a2) iseffective in improving the adhesion between the resist film and thesubstrate. In addition, by virtue of containing the structural unit(a2), for example, the acid diffusion length is appropriately adjusted,the adhesion of the resist film to the substrate is enhanced, or thesolubility during development is appropriately adjusted. As a result,the lithography properties are enhanced.

The term “lactone-containing cyclic group” refers to a cyclic groupincluding a ring containing a —O—C(═O)— structure (lactone ring). Theterm “lactone ring” refers to a single ring containing a —O—C(O)—structure, and this ring is counted as the first ring. Alactone-containing cyclic group in which the only ring structure is thelactone ring is referred to as a monocyclic group, and groups containingother ring structures are described as polycyclic groups regardless ofthe structure of the other rings. The lactone-containing cyclic groupmay be either a monocyclic group or a polycyclic group.

The lactone-containing cyclic group for the structural unit (a2) is notparticularly limited, and an arbitrary structural unit may be used.Specific examples include groups represented by general formulae(a2-r-1) to (a2-r-7) shown below.

In the formulae, each Ra′²¹ independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R¹¹ represents a hydrogen atom, an alkyl group, alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group; A″ represents an oxygen atom (—O—), asulfur atom (—S—) or an alkylene group of 1 to 5 carbon atoms which maycontain an oxygen atom or a sulfur atom; n′ represents an integer of 0to 2; and m′ represents 0 or 1.

In formulae (a2-r-1) to (a2-r-7), the alkyl group for Ra′²¹ ispreferably an alkyl group of 1 to 6 carbon atoms. Further, the alkylgroup is preferably a linear alkyl group or a branched alkyl group.Specific examples include a methyl group, an ethyl group, a propylgroup, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group, a neopentyl groupand a hexyl group. Among these, a methyl group or ethyl group ispreferable, and a methyl group is particularly desirable.

The alkoxy group for Ra′²¹ is preferably an alkoxy group of 1 to 6carbon atoms.

Further, the alkoxy group is preferably a linear or branched alkoxygroup. Specific examples of the alkoxy groups include the aforementionedalkyl groups for Ra′²¹ having an oxygen atom (—O—) bonded thereto.

As examples of the halogen atom for Ra′²¹, a fluorine atom, chlorineatom, bromine atom and iodine atom can be given. Among these, a fluorineatom is preferable.

Examples of the halogenated alkyl group for Ra′²¹ include groups inwhich part or all of the hydrogen atoms within the aforementioned alkylgroup for Ra′²¹ has been substituted with the aforementioned halogenatoms. As the halogenated alkyl group, a fluorinated alkyl group ispreferable, and a perfluoroalkyl group is particularly desirable.

With respect to —COOR″ and —OC(═O)R″ for Ra′²¹, R″ represents a hydrogenatom, an alkyl group, a lactone-containing cyclic group, acarbonate-containing cyclic group or an —SO₂— containing cyclic group.

The alkyl group for R″ may be linear, branched or cyclic, and preferablyhas 1 to 15 carbon atoms.

When R″ represents a linear or branched alkyl group, it is preferably analkyl group of 1 to 10 carbon atoms, more preferably an alkyl group of 1to 5 carbon atoms, and most preferably a methyl group or an ethyl group.

When R″ is a cyclic alkyl group (cycloalkyl group), it preferably has 3to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and mostpreferably 5 to 10 carbon atoms. Specific examples include groups inwhich one or more hydrogen atoms have been removed from amonocycloalkane or a polycycloalkane such as a bicycloalkane,tricycloalkane or tetracycloalkane which may or may not be substitutedwith a fluorine atom or a fluorinated alkyl group. Specific examplesinclude groups in which one or more hydrogen atoms have been removedfrom a monocycloalkane such as cyclopentane or cyclohexane; and groupsin which one or more hydrogen atoms have been removed from apolycycloalkane such as adamantane, norbomane, isobornane,tricyclodecane or tetracyclododecane.

Examples of the lactone-containing cyclic group for R″ include groupsrepresented by the aforementioned general formulae (a2-r-1) to (a2-r-7).

The carbonate-containing cyclic group for R″ is the same as defined forthe carbonate-containing cyclic group described later. Specific examplesof the carbonate-containing cyclic group include groups represented bygeneral formulae (ax3-r-1) to (ax3-r-3).

The —SO₂— containing cyclic group for R″ is the same as defined for the—SO₂— containing cyclic group described later. Specific examples of the—SO₂— containing cyclic group include groups represented by generalformulae (a5-r-1) to (a5-r-4).

The hydroxyalkyl group for Ra′²¹ preferably has 1 to 6 carbon atoms, andspecific examples thereof include the alkyl groups for Ra′²¹ in which atleast one hydrogen atom has been substituted with a hydroxy group.

In formulae (a2-r-2), (a2-r-3) and (a2-r-5), as the alkylene group of 1to 5 carbon atoms represented by A″, a linear or branched alkylene groupis preferable, and examples thereof include a methylene group, anethylene group, an n-propylene group and an isopropylene group. Examplesof alkylene groups that contain an oxygen atom or a sulfur atom includethe aforementioned alkylene groups in which —O— or —S— is bonded to theterminal of the alkylene group or present between the carbon atoms ofthe alkylene group. Specific examples of such alkylene groups include—O—CH₂—, —CH₂—O—CH₂—, —S—CH₂— and —CH₂—S—CH₂—. As A″, an alkylene groupof 1 to 5 carbon atoms or —O— is preferable, more preferably an alkylenegroup of 1 to 5 carbon atoms, and most preferably a methylene group.

Specific examples of the groups represented by the aforementionedgeneral formulae (a2-r-1) to (a2-r-7) are shown below.

An “—SO₂— containing cyclic group” refers to a cyclic group having aring containing —SO₂— within the ring structure thereof, i.e., a cyclicgroup in which the sulfur atom (S) within —SO₂— forms part of the ringskeleton of the cyclic group. The ring containing —SO₂— within the ringskeleton thereof is counted as the first ring. A cyclic group in whichthe only ring structure is the ring that contains —SO₂— in the ringskeleton thereof is referred to as a monocyclic group, and a groupcontaining other ring structures is described as a polycyclic groupregardless of the structure of the other rings. The —SO₂— containingcyclic group may be either a monocyclic group or a polycyclic group.

As the —SO₂— containing cyclic group, a cyclic group containing —O—SO₂—within the ring skeleton thereof, i.e., a cyclic group containing asultone ring in which —O—S— within the —O—SO₂— group forms part of thering skeleton thereof is particularly desirable.

More specific examples of the —SO₂— containing cyclic group includegroups represented by general formulas (a5-r-1) to (a5-r-4) shown below.

In the formulae, each Ra′⁵¹ independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom, an alkyl group, alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group; A″ represents an oxygen atom, a sulfuratom or an alkylene group of 1 to 5 carbon atoms which may contain anoxygen atom or a sulfur atom; and n′ represents an integer of 0 to 2.

In general formulae (a5-r-1) and (a5-r-2), A″ is the same as defined forA″ in general formulae (a2-r-2), (a2-r-3) and (a2-r-5).

Examples of the alkyl group, alkoxy group, halogen atom, halogenatedalkyl group, —COOR″, —OC(═O)R″ and hydroxyalkyl group for Ra′⁵¹ includethe same groups as those described above in the explanation of Ra′²¹ inthe general formulas (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by the aforementionedgeneral formulae (a5-r-1) to (a5-r-4) are shown below. In the formulaeshown below, “Ac” represents an acetyl group.

The term “carbonate-containing cyclic group” refers to a cyclic groupincluding a ring containing a —O—C(═O)—O— structure (carbonate ring).The term “carbonate ring” refers to a single ring containing a—O—C(═O)—O— structure, and this ring is counted as the first ring. Acarbonate-containing cyclic group in which the only ring structure isthe carbonate ring is referred to as a monocyclic group, and groupscontaining other ring structures are described as polycyclic groupsregardless of the structure of the other rings. The carbonate-containingcyclic group may be either a monocyclic group or a polycyclic group.

The carbonate-containing cyclic group is not particularly limited, andan arbitrary group may be used. Specific examples include groupsrepresented by general formulae (ax3-r-1) to (ax3-r-3) shown below.

In the formulae, each Ra′^(x31) independently represents a hydrogenatom, an alkyl group, an alkoxy group, a halogen atom, a halogenatedalkyl group, a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group ora cyano group; R″ represents a hydrogen atom, an alkyl group, alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group; A″ represents an oxygen atom, a sulfuratom or an alkylene group of 1 to 5 carbon atoms which may contain anoxygen atom or a sulfur atom; p′ represents an integer of 0 to 3; and q′represents 0 or 1.

In general formulae (ax3-r-2) and (ax3-r-3), A″ is the same as definedfor A″ in general formulae (a2-r-2), (a2-r-3) and (a2-r-5).

Examples of the alkyl group, alkoxy group, halogen atom, halogenatedalkyl group, —COOR″, —OC(═O)R″ and hydroxyalkyl group for Ra′³¹ includethe same groups as those described above in the explanation of Ra′²¹ inthe general formulas (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by the aforementionedgeneral formulae (ax3-r-1) to (ax3-r-3) are shown below.

As the structural unit (a2), a structural unit derived from an acrylateester which may have the hydrogen atom bonded to the carbon atom on theα-position substituted with a substituent is preferable.

The structural unit (a2) is preferably a structural unit represented bygeneral formula (a2-1) shown below.

In the formula, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms; Ya²¹represents a single bond or a divalent linking group; La²¹ represents—O—, —COO—, —CON(R′)—, —OCO—, —CONHCO— or —CONHCS—; and R′ represents ahydrogen atom or a methyl group; provided that, when La²¹ represents—O—, Ya²¹ does not represents —CO—; and Ra²¹ represents alactone-containing cyclic group, a carbonate-containing cyclic group oran —SO₂— containing cyclic group.

In the formula (a2-1), R is the same as defined above. As R, a hydrogenatom, an alkyl group of 1 to 5 carbon atoms or a fluorinated alkyl groupof 1 to 5 carbon atoms is preferable, and a hydrogen atom or a methylgroup is particularly desirable in terms of industrial availability.

In the formula (a2-1), the divalent linking group for Ya²¹ is notparticularly limited, and preferable examples thereof include a divalenthydrocarbon group which may have a substituent and a divalent linkinggroup containing a hetero atom. As the divalent linking group which mayhave a substituent or the divalent linking group containing a heteroatom for Ya²¹, the same divalent linking groups (divalent linking groupwhich may have a substituent or divalent linking group containing ahetero atom) described above for Ya^(x0) may be mentioned.

Ya²¹ preferably represents an ester bond [—C(═O)—O—], an ether bond(—O—), a linear or branched alkylene group, a combination of these, or asingle bond.

In the formula (a2-1), Ra²¹ represents a lactone-containing cyclicgroup, an —SO₂— containing cyclic group or a carbonate-containing cyclicgroup.

Preferable examples of the lactone-containing cyclic group, the —SO₂—containing cyclic group and the carbonate-containing cyclic group forRa²¹ include groups represented by general formulae (a2-r-1) to(a2-r-7), groups represented by general formulae (a5-r-1) to (a5-r-4)and groups represented by general formulae (ax3-r-1) to (ax3-r-3).

Among the above examples, a lactone-containing cyclic group or a —SO₂—containing cyclic group is preferable, and a group represented bygeneral formula (a2-r-1), (a2-r-2), (a2-r-6) or (a5-r-1) is morepreferable. Specifically, a group represented by any of chemicalformulae (r-lc-1-1) to (r-lc-1-7), (r-lc-2-1) to (r-lc-2-18),(r-lc-6-1), (r-sl-1-1) and (r-sl-1-18) is still more preferable.

As the structural unit (a2) contained in the component (A1-1), 1 kind ofstructural unit may be used, or 2 or more kinds of structural units maybe used.

When the component (A1-1) contains the structural unit (a2), the amountof the structural unit (a2) based on the combined total (100 mol %) ofall structural units constituting the component (A1-1) is preferably 1to 50 mol %, more preferably 5 to 45 mol %, still more preferably 10 to40 mol %, and most preferably 10 to 30 mol %.

When the amount of the structural unit (a2) is at least as large as thelower limit of the above preferable range, the effect of using thestructural unit (a2) may be satisfactorily achieved due to theaforementioned effects. On the other hand, when the amount of thestructural unit (a2) is no more than the upper limit of the abovepreferable range, a good balance may be achieved with the otherstructural units, and various lithography properties may be improved.

Structural Unit (a3):

The component (A1-1) may include, in addition to the structural unit(a0), a structural unit (a3) containing a polar group-containingaliphatic hydrocarbon group (provided that the structural units thatfall under the definition of structural units (a0), (a1) or (a2) areexcluded). When the component (A1-1) includes the structural unit (a3),the hydrophilicity of the component (A) is enhanced, therebycontributing to improvement in resolution. Further, the acid diffusionlength may be appropriately adjusted.

Examples of the polar group include a hydroxyl group, cyano group,carboxyl group, or hydroxyalkyl group in which part of the hydrogenatoms of the alkyl group have been substituted with fluorine atoms,although a hydroxyl group is particularly desirable.

Examples of the aliphatic hydrocarbon group include linear or branchedhydrocarbon groups (preferably alkylene groups) of 1 to 10 carbon atoms,and cyclic aliphatic hydrocarbon groups (cyclic groups). These cyclicgroups can be selected appropriately from the multitude of groups thathave been proposed for the resins of resist compositions designed foruse with ArF excimer lasers.

In the case where the cyclic group is a monocyclic group, the monocyclicgroup preferably has 3 to 10 carbon atoms. Of the various possibilities,structural units derived from an acrylate ester that include analiphatic monocyclic group that contains a hydroxyl group, cyano group,carboxyl group or a hydroxyalkyl group in which part of the hydrogenatoms of the alkyl group have been substituted with fluorine atoms areparticularly desirable. Examples of the monocyclic groups include groupsin which two or more hydrogen atoms have been removed from amonocycloalkane. Specific examples include groups in which one or morehydrogen atoms have been removed from a monocycloalkane such ascyclopentane, cyclohexane or cyclooctane. Of these polycyclic groups,groups in which two or more hydrogen atoms have been removed fromcyclopentane or cyclohexane are preferred industrially.

In the case where the cyclic group is a polycyclic group, the polycyclicgroup preferably has 7 to 30 carbon atoms. Of the various possibilities,structural units derived from an acrylate ester that include analiphatic polycyclic group that contains a hydroxyl group, cyano group,carboxyl group or a hydroxyalkyl group in which part of the hydrogenatoms of the alkyl group have been substituted with fluorine atoms areparticularly desirable. Examples of the polycyclic group include groupsin which two or more hydrogen atoms have been removed from abicycloalkane, tricycloalkane, tetracycloalkane or the like. Specificexamples include groups in which two or more hydrogen atoms have beenremoved from a polycycloalkane such as adamantane, norbomane,isobornane, tricyclodecane or tetracyclododecane. Of these polycyclicgroups, groups in which two or more hydrogen atoms have been removedfrom adamantane, norbornane or tetracyclododecane are preferredindustrially.

As the structural unit (a3), there is no particular limitation as longas it is a structural unit containing a polar group-containing aliphatichydrocarbon group, and an arbitrary structural unit may be used.

The structural unit (a3) is preferably a structural unit derived from anacrylate ester which may have the hydrogen atom bonded to the carbonatom on the α-position substituted with a substituent and contains apolar group-containing aliphatic hydrocarbon group.

When the aliphatic hydrocarbon group within the polar group-containingaliphatic hydrocarbon group is a linear or branched hydrocarbon group of1 to 10 carbon atoms, the structural unit (a3) is preferably astructural unit derived from a hydroxyethyl ester of acrylic acid.

On the other hand, in the structural unit (a3), when the hydrocarbongroup within the polar group-containing aliphatic hydrocarbon group is apolycyclic group, structural units represented by formulas (a3-1),(a3-2), (a3-3) and (a3-4) shown below are preferable.

In the formulas, R is the same as defined above; j is an integer of 1 to3; k is an integer of 1 to 3; t′ is an integer of 1 to 3; l is aninteger of 0 to 5; and s is an integer of 1 to 3.

In formula (a3-1), j is preferably 1 or 2, and more preferably 1. When jis 2, it is preferable that the hydroxyl groups be bonded to the 3rd and5th positions of the adamantyl group. When j is 1, it is preferable thatthe hydroxyl group be bonded to the 3rd position of the adamantyl group.

j is preferably 1, and it is particularly desirable that the hydroxylgroup be bonded to the 3rd position of the adamantyl group.

In formula (a3-2), k is preferably 1. The cyano group is preferablybonded to the 5th or 6th position of the norbomyl group.

In formula (a3-3), t′ is preferably 1. l is preferably 1. s ispreferably 1. Further, it is preferable that a 2-norbomyl group or3-norbomyl group be bonded to the terminal of the carboxy group of theacrylic acid. The fluorinated alkyl alcohol is preferably bonded to the5th or 6th position of the norbomyl group.

In formula (a3-4), t′ is preferably 1 or 2. l is preferably 0 or 1. s ispreferably 1. The fluorinated alkyl alcohol is preferably bonded to the3rd or 5th position of the cyclohexyl group.

As the structural unit (a3) contained in the component (A1-1), 1 kind ofstructural unit may be used, or 2 or more kinds of structural units maybe used.

When the component (A1-1) contains the structural unit (a3), the amountof the structural unit (a3) within the component (A1-1) based on thecombined total (100 mol %) of all structural units constituting thecomponent (A1) is preferably 1 to 30 mol %, more preferably 2 to 25 mol%, and still more preferably 5 to 20 mol %.

When the amount of the structural unit (a3) is at least as large as thelower limit of the above preferable range, the effect of using thestructural unit (a3) may be satisfactorily achieved due to theaforementioned effects. On the other hand, when the amount of thestructural unit (a3) is no more than the upper limit of the abovepreferable range, a good balance may be achieved with the otherstructural units, and various lithography properties may be improved.

Structural Unit (a9):

The component (A1-1) may include, in addition to the structural unit(a0), a structural unit (a9) represented by general formula (a9-1) shownbelow.

In the formula, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms; Ya⁹¹represents a single bond or a divalent linking group; Ya⁹² represents adivalent linking group; and R⁹¹ represents a hydrocarbon group which mayhave a substituent.

In the general formula (a9-1), R is the same as defined above.

As R, a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or afluorinated alkyl group of 1 to 5 carbon atoms is preferable, and ahydrogen atom or a methyl group is particularly desirable in terms ofindustrial availability.

In formula (a9-1), the divalent linking group for Ya⁹¹ is the same asdefined for the divalent linking group (divalent hydrocarbon group whichmay have a substituent, a divalent linking group containing a heteroatom) for Ya^(x0) described above. Among these, Ya⁹¹ is preferably asingle bond.

In formula (a9-1), the divalent linking group for Ya⁹² is the same asdefined for the divalent linking group (divalent hydrocarbon group whichmay have a substituent, a divalent linking group containing a heteroatom) for Ya^(x0) described above.

With respect to the divalent linking group for Ya⁹², as the divalenthydrocarbon group which may have a substituent, a linear or branchedaliphatic hydrocarbon group is preferable.

In the case where Ya⁹² represents a divalent linking group containing ahetero atom, examples of the linking group include —O—, —C(═O)—O—,—C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —NH—, —NH—C(═NH)— (wherein H may besubstituted with a substituent such as an alkyl group or an acyl group),—S—, —S(═O)₂—, —S(═O)₂—O—, C(═S), a group represented by general formula—Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹,—[Y²¹—C(═O)—O]_(m′)—Y²²— or —Y²¹—O—C(═O)—Y²²— [in the formulae, Y²¹ andY²² each independently represents a divalent hydrocarbon group which mayhave a substituent, and O represents an oxygen atom; and m′ representsan integer of 0 to 3. Among these examples, —C(═O)— and —C(═S)— arepreferable.

In general formula (a9-1), examples of the hydrocarbon group for R⁹¹include an alkyl group, a monovalent alicyclic hydrocarbon group, anaryl group and an aralkyl group.

The alkyl group for R⁹¹ preferably has 1 to 8 carbon atoms, morepreferably 1 to 6 carbon atoms, and still more preferably 1 to 4 carbonatoms. The alkyl group may be linear or branched. Specific examples ofpreferable alkyl groups include a methyl group, an ethyl group, a propylgroup, a butyl group, a hexyl group and an octyl group.

The monovalent alicyclic hydrocarbon group for R⁹¹ preferably has 3 to20 carbon atoms, and more preferably 3 to 12 carbon atoms. Themonovalent alicyclic hydrocarbon group may be polycyclic or monocyclic.As the monocyclic alicyclic hydrocarbon group, a group in which one ormore hydrogen atoms have been removed from a monocycloalkane ispreferable. The monocycloalkane preferably has 3 to 6 carbon atoms, andspecific examples thereof include cyclobutane, cyclopentane andcyclohexane. As the polycyclic alicyclic hydrocarbon group, a group inwhich one or more hydrogen atoms have been removed from apolycycloalkane is preferable, and the polycyclic group preferably has 7to 12 carbon atoms. Examples of the polycycloalkane include adamantane,norbornane, isobornane, tricyclodecane and tetracyclododecane.

The aryl group for R⁹¹ preferably has 6 to 18 carbon atoms, and morepreferably 6 to 10 carbon atoms. Specifically, a phenyl group isparticularly desirable.

As the aralkyl group for R⁹¹, an aralkyl group in which an alkylenegroup having 1 to 8 carbon atoms has been bonded to the aforementioned“aryl group for R⁹¹” is preferable, an aralkyl group in which analkylene group of 1 to 6 carbon atoms has been bonded to theaforementioned “aryl group for R⁹¹” is more preferable, and an aralkylgroup in which an alkylene group having 1 to 4 carbon atoms has beenbonded to the aforementioned “aryl group for R⁹¹” is most preferable.

The hydrocarbon group for R⁹¹ preferably has part or all of the hydrogenatoms within the hydrocarbon group substituted with fluorine, and thehydrocarbon group more preferably has 30 to 100% of the hydrogen atomssubstituted with fluorine. Among these, a perfluoroalkyl group in whichall of the hydrogen atoms within the alkyl group have been substitutedwith fluorine atoms is particularly desirable.

The hydrocarbon group for R⁹¹ may have a substituent. Examples of thesubstituent include a halogen atom, an oxo group (═O), a hydroxy group(—OH), an amino group (—NH₂) and —SO₂—NH₂. Further, part of the carbonatoms constituting the hydrocarbon group may be substituted with asubstituent containing a hetero atom. Examples of the substituentcontaining a hetero atom include —O—, —NH—, —N═, —C(═O)—O—, —S—,—S(═O)₂— and —S(═O)₂—O—.

As the hydrocarbon group for R⁹¹, examples of the hydrocarbon grouphaving a substituent include lactone-containing cyclic groupsrepresented by the aforementioned general formulae (a2-r-1) to (a2-r-7).

Further, as R⁹¹, examples of the hydrocarbon group having a substituentinclude —SO₂— containing cyclic groups represented by general formulae(a5-r-1) to (a5-r-4); and substituted aryl groups and monocyclicheterocyclic groups represented by chemical formulae shown below.

As the structural unit (a9), a structural unit represented by generalformula (a9-1-1) shown below is preferable.

In the formula, R is the same as defined above; Ya⁹¹ represents a singlebond or a divalent linking group; R⁹¹ represents a hydrocarbon groupoptionally having a substituent; and Ya⁹² represents an oxygen atom or asulfur atom.

In general formula (a9-1-1), Ya⁹¹, R⁹¹ and R are the same as definedabove.

R⁹² represents an oxygen atom or a sulfur atom.

Specific examples of structural units represented by general formula(a9-1) or (a9-1-1) are shown below. In the following formulae, Rarepresents a hydrogen atom, a methyl group or a trifluoromethyl group.

As the structural unit (a9) contained in the component (A1-1), 1 kind ofstructural unit may be used, or 2 or more kinds may be used.

When the component (A1-1) contains the structural unit (a9), the amountof the structural unit (a9) based on the combined total (100 mol %) ofall structural units constituting the component (A1-1) is preferably 1to 40 mol %, more preferably 3 to 30 mol %, still more preferably 5 to25 mol %, and most preferably 10 to 20 mol %.

When the amount of the structural unit (a9) is at least as large as thelower limit of the above-mentioned range, for example, the aciddiffusion length may be appropriately adjusted, the adhesion of theresist film to a substrate may be enhanced, the solubility duringdevelopment may be appropriately adjusted, and the etching resistancemay be improved. On the other hand, when the amount of the structuralunit (a9) is no more than the upper limit of the above-mentioned range,a good balance may be achieved with the other structural units, and thelithography properties may be improved.

In the resist composition, as the component (A1-1), one kind of compoundmay be used, or two or more kinds of compounds may be used incombination.

In the resist composition of the present embodiment, the component(A1-1) is a polymeric compound having the structural unit (a0), andpreferable examples thereof include a copolymer having any other desiredstructural unit.

Preferable examples of the component (A1-1) include a polymeric compoundhaving a repeating structure of the structural units (a0) and (a0-2);and a polymeric compound having a repeating structure of the structuralunits (a0), (a2) and (a3).

The component (A1-1) may be produced, for example, by dissolving themonomers corresponding with each of the structural units in apolymerization solvent, followed by addition of a radical polymerizationinitiator such as azobisisobutyronitrile (AIBN) ordimethyl-2,2′-azobisisoutyrate (e.g., V-601). Alternatively, thecomponent (A1) can be prepared by dissolving a monomer from which thestructural unit (a0) is derived, and a precursor monomer (monomer forwhich the functional group is protected) from which the structural unitother than the structural unit (a0) is derived in a polymerizationsolvent, polymerizing the dissolved monomers using the radicalpolymerization initiator described above, followed by performing adeprotection reaction. In the polymerization, a chain transfer agentsuch as HS—CH₂—CH₂—CH₂—C(CF₃)₂—OH may be used to introduce a —C(CF₃)₂—OHgroup at the terminal(s) of the polymer. Such a copolymer havingintroduced a hydroxyalkyl group in which some of the hydrogen atoms ofthe alkyl group are substituted with fluorine atoms is effective inreducing developing defects and LER (line edge roughness: unevenness ofthe side walls of a line pattern).

The weight average molecular weight (Mw) (the polystyrene equivalentvalue determined by gel permeation chromatography (GPC)) of thecomponent (A1-1) is not particularly limited, but is preferably 1,000 to50,000, more preferably 2,000 to 30,000, and still more preferably 3,000to 20,000.

When the Mw of the component (A1-1) is no more than the upper limit ofthe above-mentioned range, the resist composition exhibits asatisfactory solubility in a resist solvent. On the other hand, when theMw of the component (A1-1) is at least as large as the lower limit ofthe above-mentioned range, dry etching resistance and thecross-sectional shape of the resist pattern becomes satisfactory.

The dispersity (Mw/Mn) of the component (A1-1) is not particularlylimited, but is preferably 1.0 to 4.0, more preferably 1.0 to 3.0, andmost preferably 1.1 to 2.0. Here, Mn is the number average molecularweight.

Base Component Other than (A1-1)

In the resist composition of the present embodiment, as the component(A), “a base component which exhibits changed solubility in a developingsolution under action of acid” other than the component (A1-1) may beused in combination. Such base component other than the component (A1-1)is not particularly limited, and any of the multitude of conventionalbase components used within chemically amplified resist compositions maybe appropriately selected for use. As such base component other than thecomponent (A1-1), one kind of a polymer or a low molecular weightcompound may be used, or a combination of two or more kinds may be used.

In the resist composition of the present embodiment, the amount of thecomponent (A) may be appropriately adjusted depending on the thicknessof the resist film to be formed, and the like.

<Component (B)>

In the resist composition of the present embodiment, the component (B)includes a compound (B1) represented by general formula (b1) shown below(hereafter, sometimes referred to as “component (B1)”).

In formula (b1-1), R^(b11) represents a cyclic group which may have asubstituent; R^(b10), R^(b20) and R^(b30) each independently representsa substituent; n_(b1) represents an integer of 0 to 4; n_(b2) representsan integer of 0 to 5; n_(b3) represents an integer of 0 to 5; and X⁻represents a counteranion.

Component (B1)

Component (B1) is a sulfonium salt having a cation moiety with aspecific structure and an anion moiety.

Cation Moiety of Component (B1)

In formula (b1-1), R^(b11) represents a cyclic group which may have asubstituent. The cyclic group is preferably a cyclic hydrocarbon group,and the cyclic hydrocarbon group may be either an aromatic hydrocarbongroup or an aliphatic hydrocarbon group. An “aliphatic hydrocarbongroup” refers to a hydrocarbon group that has no aromaticity. Thealiphatic hydrocarbon group may be either saturated or unsaturated, butin general, the aliphatic hydrocarbon group is preferably saturated. Thecyclic hydrocarbon group for R^(b11) may contain a hetero atom, such asa hetero ring.

The aromatic hydrocarbon group for R^(b11) is a hydrocarbon group havingan aromatic ring. The aromatic hydrocarbon group preferably has 3 to 30carbon atoms, more preferably 5 to 30 carbon atoms, still morepreferably 5 to 20 carbon atoms, still more preferably 6 to 15 carbonatoms, and most preferably 6 to 12 carbon atoms. Here, the number ofcarbon atoms within a substituent(s) is not included in the number ofcarbon atoms of the aromatic hydrocarbon group.

Specific examples of the aromatic ring contained in the aromatichydrocarbon group for R^(b11) include benzene, fluorene, naphthalene,anthracene, phenanthrene, biphenyl, or an aromatic hetero ring in whichpart of the carbon atoms constituting any one of these aromatic ringshave been substituted with a hetero atom. Examples of the hetero atomwithin the aromatic hetero rings include an oxygen atom, a sulfur atomand a nitrogen atom. In terms of compatibility with the component (A),the aromatic ring contained in the aromatic hydrocarbon group forR^(b11) preferably contains no hetero atom, and more preferably anaromatic ring such as benzene, fluorene, naphthalene, anthracene,phenanthrene or biphenyl.

Specific examples of the aromatic hydrocarbon group for R^(b11) includea group in which 1 hydrogen atom has been removed from theaforementioned aromatic ring (an aryl group, such as a phenyl group or anaphthyl group), and a group in which 1 hydrogen atom of theaforementioned aromatic ring has been substituted with an alkylene group(an arylalkyl group, such as a benzyl group, a phenethyl group, a1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethylgroup, or a 2-naphthylethyl group). The alkylene group (alkyl chainwithin the arylalkyl group) preferably has 1 to 4 carbon atom, morepreferably 1 or 2, and most preferably 1.

Examples of the cyclic aliphatic hydrocarbon group for R^(b11) includealiphatic hydrocarbon groups containing a ring in the structure thereof.

As examples of the hydrocarbon group containing a ring in the structurethereof, an alicyclic hydrocarbon group (a group in which one hydrogenatom has been removed from an aliphatic hydrocarbon ring), a group inwhich the alicyclic hydrocarbon group is bonded to the terminal of theaforementioned chain-like aliphatic hydrocarbon group, and a group inwhich the alicyclic group is interposed within the aforementioned linearor branched aliphatic hydrocarbon group, can be given.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, andmore preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be either a polycyclic group or amonocyclic group. As the monocyclic alicyclic hydrocarbon group, a groupin which one or more hydrogen atoms have been removed from amonocycloalkane is preferable. The monocycloalkane preferably has 3 to 6carbon atoms, and specific examples thereof include cyclopentane andcyclohexane. As the polycyclic alicyclic hydrocarbon group, a group inwhich one or more hydrogen atoms have been removed from apolycycloalkane is preferable, and the polycyclic group preferably has 7to 30 carbon atoms. Among polycycloalkanes, a polycycloalkane having abridged ring polycyclic skeleton, such as adamantane, norbornane,isobornane, tricyclodecane or tetracyclodpdecane, and a polycycloalkanehaving a condensed ring polycyclic skeleton, such as a cyclic grouphaving a steroid skeleton are preferable.

Among these examples, as the cyclic aliphatic hydrocarbon group forR^(b11), a group in which 1 or more hydrogen atoms have been removedfrom a monocycloalkane or a polycycloalkane is preferable, a group inwhich 1 or more hydrogen atoms have been removed from a monocycloalkaneis more preferable, and a group in which 1 or more hydrogen atoms havebeen removed from cyclopentane or cyclohexane is most preferable.

The linear aliphatic hydrocarbon group which may be bonded to thealicyclic hydrocarbon group preferably has 1 to 10 carbon atoms, morepreferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbonatoms, and most preferably 1 to 3 carbon atoms. As the linear aliphatichydrocarbon group, a linear alkylene group is preferable. Specificexamples thereof include a methylene group [—CH₂—], an ethylene group[—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], a tetramethylene group[—(CH₂)₄—] and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group which may be bonded to thealicyclic hydrocarbon group preferably has 2 to 10 carbon atoms, morepreferably 3 to 6 carbon atoms, still more preferably 3 or 4 carbonatoms, and most preferably 3 carbon atoms. As the branched aliphatichydrocarbon group, branched alkylene groups are preferred, and specificexamples include various alkylalkylene groups, including alkylmethylenegroups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—,—C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—; alkylethylene groups such as—CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and—C(CH₂CH₃)₂—CH₂—; alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and—CH₂CH(CH₃)CH₂—; and alkyltetramethylene groups such as—CH(CH₃)CH₂CH₂CH₂—, and —CH₂CH(CH₃)CH₂CH₂—. As the alkyl group withinthe alkylalkylene group, a linear alkyl group of 1 to 5 carbon atoms ispreferable.

Further, examples of the cyclic group for R^(b11) also include—COOR^(XYZ) and —OC(═O)R^(XYZ), wherein R^(XYZ) is a lactone-containingcyclic group, a carbonate-containing cyclic group or an —SO₂-containingcyclic group.

As the substituent for the cyclic group for R^(b11), an alkyl group, analkoxy group, a halogen atom, a halogenated alkyl group, a hydroxylgroup, a nitro group, a carbonyl group, or the like may be used.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, ethoxy group,n-propoxy group, iso-propoxy group, n-butoxy group or tert-butoxy group,and most preferably a methoxy group or an ethoxy group.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

Example of the aforementioned halogenated alkyl group includes a groupin which a part or all of the hydrogen atoms within an alkyl group of 1to 5 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group,an n-butyl group or a tert-butyl group) have been substituted with theaforementioned halogen atoms.

The carbonyl group as the substituent is a group that substitutes amethylene group (—CH₂—) constituting the cyclic hydrocarbon group.

Among these examples, in terms of compatibility with the component (A),as the substituent for the cyclic group represented by R^(b11), an alkylgroup, a halogen atom or a halogenated alkyl group is preferable, and analkyl group is more preferable.

In formula (b1-1), R^(b10), R^(b20) and R^(b30) each independentlyrepresents a substituent.

Examples of the substituent for R^(b10), R^(b20) and R^(b30) include analkyl group, a halogen atom, a halogenated alkyl group, a carbonylgroup, a cyano group, an amino group, an aryl group, and groupsrepresented by general formulae (ca-r-1) to (ca-r-7) shown below.

In the formulae, each R′²⁰¹ independently represents a hydrogen atom, acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent, or a chain-like alkenyl group which mayhave a substituent.

In formulae (ca-r-1) to (ca-r-7), the cyclic group which may have asubstituent for R′²⁰¹ is the same as defined for R^(b11) in theaforementioned formula (b1-1).

The chain alkyl group for R′²⁰¹ may be linear or branched.

The linear alkyl group preferably has 1 to 20 carbon atoms, morepreferably 1 to 15 carbon atoms, and still more preferably 1 to 10carbon atoms. Specific examples include a methyl group, an ethyl group,a propyl group, a butyl group, a pentyl group, a hexyl group, a heptylgroup, an octyl group, a nonyl group, a decyl group, an undecyl group, adodecyl group, a tridecyl group, an isotridecyl group, a tetradecylgroup, a pentadecyl group, a hexadecyl group, an isohexadecyl group, aheptadecyl group, an octadecyl group, a nonadecyl group, an icosylgroup, a henicosyl group and a docosyl group.

The branched alkyl group preferably has 3 to 20 carbon atoms, morepreferably 3 to 15 carbon atoms, and still more preferably 3 to 10carbon atoms. Specific examples thereof include a 1-methylethyl group, a1,1-dimethylethyl group, a 1-methylpropyl group, a 2-methylpropyl group,a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentyl group, a2-methylpentyl group, a 3-methylpentyl group, and a 4-methylpentylgroup.

In formulae (ca-r-1) to (ca-r-7), the chain alkenyl group for R′²⁰¹ maybe linear or branched, and preferably has 2 to 10 carbon atoms, morepreferably 2 to 5 carbon atoms, still more preferably 2 to 4 carbonatoms, and most preferably 3 carbon atoms. Examples of linear alkenylgroups include a vinyl group, a propenyl group (an allyl group) and abutynyl group. Examples of branched alkenyl groups include a1-methylvinyl group, a 2-methylvinyl group, a 1-methylpropenyl group anda 2-methylpropenyl group.

Among these examples, as the chain-like alkenyl group, a linear alkenylgroup is preferable, a vinyl group or a propenyl group is morepreferable, and a vinyl group is most preferable.

In formulae (ca-r-1) to (ca-r-7), as the substituent for the chain alkylgroup or chain alkenyl group for R′²⁰¹, an alkoxy group, a halogen atom(a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or thelike), a halogenated alkyl group, a hydroxyl group, a carbonyl group, anitro group, an amino group, a cyclic group for R′²⁰¹ may be used.

Alternatively, in formulae (ca-r-1) to (ca-r-7), the cyclic group (whichmay have a substituent) or the chain alkyl group (which may have asubstituent) represented by R′²⁰¹ may be the same as defined for theacid dissociable group represented by the aforementioned formula(a1-r-2).

In formula (b1-1), n_(b1) represents an integer of 0 to 4, preferably aninteger of 0 to 2, and more preferably 0 or 1.

n_(b2) represents an integer of 0 to 5, preferably an integer of 0 to 2,and more preferably 0 or 1.

n_(b3) represents an integer of 0 to 5, preferably an integer of 0 to 2,and more preferably 0 or 1.

Specific examples of preferable cations for the component (B1) includecations represented by formulas (b1-1-ca1) to (b1-1-ca3) shown below.

Anion Moiety of Component (B1)

In formula (b1-1), X⁻ represents a counteranion.

X⁻ is not particularly limited, and any anion known as an anion moietyof an acid-generator component for a resist composition may beappropriately selected.

Examples of X⁻ include an anion represented by general formula(b1-1-an1) shown below, an anion represented by general formula(b1-1-an2) shown below, and an anion represented by general formula(b1-1-an3) shown below.

In the formulae, R¹⁰¹ and R¹⁰⁴ to R¹⁰⁸ each independently represents acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent, provided that R¹⁰⁴ and R¹⁰⁵ may be mutually bondedto form a ring structure; R¹⁰² represents a fluorine atom or afluorinated alkyl group having 1 to 5 carbon atoms; Y¹⁰¹ represents asingle bond or a divalent group containing an oxygen atom; V¹⁰¹ to V¹⁰³each independently represents a single bond, an alkylene group or afluorinated alkylene group; L¹⁰¹ and L¹⁰² each independently representsa single bond or an oxygen atom; and L¹⁰³ to L¹⁰⁵ each independentlyrepresents a single bond, —CO— or —SO₂—.

Anion Represented by General Formula (b1-1-an1)

In the formula (b1-1-an1), R¹⁰¹ represents a cyclic group which may havea substituent, a chain-like alkyl group which may have a substituent ora chain-like alkenyl group which may have a substituent.

Cyclic Group which May have a Substituent:

The cyclic group is preferably a cyclic hydrocarbon group, and thecyclic hydrocarbon group may be either an aromatic hydrocarbon group oran aliphatic hydrocarbon group. An “aliphatic hydrocarbon group” refersto a hydrocarbon group that has no aromaticity. The aliphatichydrocarbon group may be either saturated or unsaturated, but ingeneral, the aliphatic hydrocarbon group is preferably saturated.

The aromatic hydrocarbon group for R¹⁰¹ is a hydrocarbon group having anaromatic ring. The aromatic hydrocarbon ring preferably has 3 to 30carbon atoms, more preferably 5 to 30, still more preferably 5 to 20,still more preferably 6 to 15, and most preferably 6 to 10. Here, thenumber of carbon atoms within a substituent(s) is not included in thenumber of carbon atoms of the aromatic hydrocarbon group.

Examples of the aromatic ring contained in the aromatic hydrocarbongroup represented by R¹⁰¹ include benzene, fluorene, naphthalene,anthracene, phenanthrene and biphenyl; and aromatic hetero rings inwhich part of the carbon atoms constituting the aforementioned aromaticrings has been substituted with a hetero atom. Examples of the heteroatom within the aromatic hetero rings include an oxygen atom, a sulfuratom and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group represented by R¹⁰¹include a group in which one hydrogen atom has been removed from theaforementioned aromatic ring (i.e., an aryl group, such as a phenylgroup or a naphthyl group), and a group in which one hydrogen of theaforementioned aromatic ring has been substituted with an alkylene group(e.g., an arylalkyl group such as a benzyl group, a phenethyl group, a1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethylgroup or a 2-naphthylethyl group). The alkylene group (alkyl chainwithin the arylalkyl group) preferably has 1 to 4 carbon atom, morepreferably 1 or 2, and most preferably 1.

Examples of the cyclic aliphatic hydrocarbon group for R¹⁰¹ includealiphatic hydrocarbon groups containing a ring in the structure thereof.

As examples of the hydrocarbon group containing a ring in the structurethereof, an alicyclic hydrocarbon group (a group in which one hydrogenatom has been removed from an aliphatic hydrocarbon ring), a group inwhich the alicyclic hydrocarbon group is bonded to the terminal of theaforementioned chain-like aliphatic hydrocarbon group, and a group inwhich the alicyclic group is interposed within the aforementioned linearor branched aliphatic hydrocarbon group, can be given.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, andmore preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be either a polycyclic group or amonocyclic group. As the monocyclic alicyclic hydrocarbon group, a groupin which one or more hydrogen atoms have been removed from amonocycloalkane is preferable. The monocycloalkane preferably has 3 to 6carbon atoms, and specific examples thereof include cyclopentane andcyclohexane. As the polycyclic alicyclic hydrocarbon group, a group inwhich one or more hydrogen atoms have been removed from apolycycloalkane is preferable, and the polycyclic group preferably has 7to 30 carbon atoms. Among polycycloalkanes, a polycycloalkane having abridged ring polycyclic skeleton, such as adamantane, norbomane,isobornane, tricyclodecane or tetracyclodpdecane, and a polycycloalkanehaving a condensed ring polycyclic skeleton, such as a cyclic grouphaving a steroid skeleton are preferable.

Among these examples, as the cyclic aliphatic hydrocarbon group forR¹⁰¹, a group in which one or more hydrogen atoms have been removed froma monocycloalkane or a polycycloalkane is preferable, a group in whichone or more hydrogen atoms have been removed from a polycycloalkane ismore preferable, an adamantyl group or a norbomyl group is still morepreferable, and an adamantyl group is most preferable.

The linear aliphatic hydrocarbon group which may be bonded to thealicyclic hydrocarbon group preferably has 1 to 10 carbon atoms, morepreferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbonatoms, and most preferably 1 to 3 carbon atoms. As the linear aliphatichydrocarbon group, a linear alkylene group is preferable. Specificexamples thereof include a methylene group [—CH₂—], an ethylene group[—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], a tetramethylene group[—(CH₂)₄—] and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group which may be bonded to thealicyclic hydrocarbon group preferably has 2 to 10 carbon atoms, morepreferably 3 to 6 carbon atoms, still more preferably 3 or 4 carbonatoms, and most preferably 3 carbon atoms. As the branched aliphatichydrocarbon group, branched alkylene groups are preferred, and specificexamples include various alkylalkylene groups, including alkylmethylenegroups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—,—C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—; alkylethylene groups such as—CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and—C(CH₂CH₃)₂—CH₂—; alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and—CH₂CH(CH₃)CH₂—; and alkyltetramethylene groups such as—CH(CH₃)CH₂CH₂CH₂—, and —CH₂CH(CH₃)CH₂CH₂—. As the alkyl group withinthe alkylalkylene group, a linear alkyl group of 1 to 5 carbon atoms ispreferable.

The cyclic hydrocarbon group for R¹⁰¹ may contain a hetero atom such asa heterocycle. Specific examples include lactone-containing cyclicgroups represented by the aforementioned general formulae (a2-r-1) to(a2-r-7), the —SO₂— containing cyclic group represented by theaforementioned formulae (a5-r-1) to (a5-r-4), and other heterocyclicgroups represented by the aforementioned chemical formulae (r-hr-1) to(r-hr-16).

As the substituent for the cyclic group for R¹⁰¹, an alkyl group, analkoxy group, a halogen atom, a halogenated alkyl group, a hydroxylgroup, a carbonyl group, a nitro group or the like can be used.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is particularly desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, ethoxy group,n-propoxy group, iso-propoxy group, n-butoxy group or tert-butoxy group,and most preferably a methoxy group or an ethoxy group.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

Example of the aforementioned halogenated alkyl group includes a groupin which a part or all of the hydrogen atoms within an alkyl group of 1to 5 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group,an n-butyl group or a tert-butyl group) have been substituted with theaforementioned halogen atoms.

The carbonyl group as the substituent is a group that substitutes amethylene group (—CH₂—) constituting the cyclic hydrocarbon group.

Chain Alkyl Group which May have a Substituent:

The chain-like alkyl group for R¹⁰¹ may be linear or branched.

The linear alkyl group preferably has 1 to 20 carbon atoms, morepreferably 1 to 15, and most preferably 1 to 10. Specific examplesinclude a methyl group, an ethyl group, a propyl group, a butyl group, apentyl group, a hexyl group, a heptyl group, an octyl group, a nonylgroup, a decyl group, an undecyl group, a dodecyl group, a tridecylgroup, an isotridecyl group, a tetradecyl group, a pentadecyl group, ahexadecyl group, an isohexadecyl group, a heptadecyl group, an octadecylgroup, a nonadecyl group, an icosyl group, a henicosyl group and adocosyl group.

The branched alkyl group preferably has 3 to 20 carbon atoms, morepreferably 3 to 15, and most preferably 3 to 10. Specific examplesinclude a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropylgroup, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutylgroup, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentylgroup, a 2-methylpentyl group, a 3-methylpentyl group and a4-methylpentyl group.

Chain Alkenyl Group which May have a Substituent:

The chain-like alkenyl group for R¹⁰¹ may be linear or branched, andpreferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbonatoms, still more preferably 2 to 4 carbon atoms, and most preferably 3carbon atoms. Examples of linear alkenyl groups include a vinyl group, apropenyl group (an allyl group) and a butynyl group. Examples ofbranched alkenyl groups include a 1-methylvinyl group, a 2-methylvinylgroup, a 1-methylpropenyl group and a 2-methylpropenyl group.

Among these examples, as the chain-like alkenyl group, a linear alkenylgroup is preferable, a vinyl group or a propenyl group is morepreferable, and a vinyl group is most preferable.

As the substituent for the chain-like alkyl group or alkenyl group forR¹⁰¹, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxyl group, a carbonyl group, a nitro group, an amino group, acyclic group for R¹⁰¹ or the like can be used.

Among the above examples, as R¹⁰¹, a cyclic group which may have asubstituent is preferable, and a cyclic hydrocarbon group which may havea substituent is more preferable. Specifically, a phenyl group, anaphthyl group, a group in which one or more hydrogen atoms have beenremoved from a polycycloalkane, a lactone-containing cyclic grouprepresented by any one of the aforementioned formula (a2-r-1) to(a2-r-7), or an —SO₂— containing cyclic group represented by any one ofthe aforementioned formula (a5-r-1) to (a5-r-4) is preferable, and agroup in which one or more hydrogen atoms have been removed from apolycycloalkane is more preferable.

In formula (b1-1-an1), Y¹⁰¹ represents a single bond or a divalentlinking group containing an oxygen atom.

In the case where Y¹⁰¹ is a divalent linking group containing an oxygenatom, Y¹⁰¹ may contain an atom other than an oxygen atom. Examples ofatoms other than an oxygen atom include a carbon atom, a hydrogen atom,a sulfur atom and a nitrogen atom.

Examples of divalent linking groups containing an oxygen atom includenon-hydrocarbon, oxygen atom-containing linking groups such as an oxygenatom (an ether bond; —O—), an ester bond (—C(═O)—O—), an oxycarbonylgroup (—O—C(═O)—), an amido bond (—C(═O)—NH—), a carbonyl group(—C(═O)—) and a carbonate bond (—O—C(═O)—O—); and combinations of theaforementioned non-hydrocarbon, hetero atom-containing linking groupswith an alkylene group. Furthermore, the combinations may have asulfonyl group (—SO₂—) bonded thereto. Examples of divalent linkinggroups containing an oxygen atom include linking groups represented bygeneral formulae (y-a1-1) to (y-a1-7) shown below.

In the formulae, V′¹⁰¹ represents a single bond or an alkylene group of1 to 5 carbon atoms; V′¹⁰² represents a divalent saturated hydrocarbongroup of 1 to 30 carbon atoms.

The divalent saturated hydrocarbon group for V′¹⁰² is preferably analkylene group of 1 to 30 carbon atoms, more preferably an alkylenegroup of 1 to 10 carbon atoms, and still more preferably an alkylenegroup of 1 to 5 carbon atoms.

The alkylene group for V′¹⁰¹ and V′¹⁰² may be a linear alkylene group ora branched alkylene group, and a linear alkylene group is preferable.

Specific examples of the alkylene group for V′¹⁰¹ and V′¹⁰² include amethylene group [—CH₂—]; an alkylmethylene group, such as —CH(CH₃)—,—CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)— and—C(CH₂CH₃)₂—; an ethylene group [—CH₂CH₂—]; an alkylethylene group, suchas —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂— and —CH(CH₂CH₃)CH₂—; atrimethylene group (n-propylene group) [—CH₂CH₂CH₂—]; analkyltrimethylene group, such as —CH(CH₃)CH₂CH₂— and —CH₂CH(CH₃)CH₂—; atetramethylene group [—CH₂CH₂CH₂CH₂—]; an alkyltetramethylene group,such as —CH(CH₃)CH₂CH₂CH₂—, —CH₂CH(CH₃)CH₂CH₂—; and a pentamethylenegroup [—CH₂CH₂CH₂CH₂CH₂—].

Further, part of methylene group within the alkylene group for V′¹⁰¹ andV′¹⁰² may be substituted with a divalent aliphatic cyclic group of 5 to10 carbon atoms. The aliphatic cyclic group is preferably a divalentgroup in which one hydrogen atom has been removed from the cyclicaliphatic hydrocarbon group (monocyclic aliphatic hydrocarbon group orpolycyclic aliphatic hydrocarbon group) for Ra′³ in the aforementionedformula (a1-r-1), and a cyclohexylene group, 1,5-adamantylene group or2,6-adamantylene group is preferable.

Y¹⁰¹ is preferably a divalent linking group containing an ether bond ora divalent linking group containing an ester bond, and groupsrepresented by the aforementioned formulas (y-a1-1) to (y-a1-5) arepreferable.

In formula (b1-1-an1), V¹⁰¹ represents a single bond, an alkylene groupor a fluorinated alkylene group. The alkylene group and the fluorinatedalkylene group for V¹⁰¹ preferably has 1 to 4 carbon atoms. Examples ofthe fluorinated alkylene group for V¹⁰¹ include a group in which part orall of the hydrogen atoms within the alkylene group for V¹⁰¹ have beensubstituted with fluorine. Among these examples, as V¹⁰¹, a single bondor a fluorinated alkylene group of 1 to 4 carbon atoms is preferable.

In formula (b1-1-an1), R¹⁰² represents a fluorine atom or a fluorinatedalkyl group of 1 to 5 carbon atoms. R¹⁰² is preferably a fluorine atomor a perfluoroalkyl group of 1 to 5 carbon atoms, and more preferably afluorine atom.

As a specific example of the anion moiety represented by theaforementioned formula (b1-1-an1), in the case where Y¹⁰¹ a single bond,a fluorinated alkylsulfonate anion such as a trifluoromethanesulfonateanion or a perfluorobutanesulfonate anion can be mentioned; and in thecase where Y¹⁰¹ represents a divalent linking group containing an oxygenatom, anions represented by formulae (an-1) to (an-3) shown below can bementioned.

In the formulae, R″¹⁰¹ represents an aliphatic cyclic group which mayhave a substituent, a monovalent heterocyclic group represented by anyof Formulae (r-hr-1) to (r-hr-6), or a chain-like alkyl group which mayhave a substituent; R″¹⁰² represents an aliphatic cyclic group which mayhave a substituent, a lactone-containing cyclic group represented by anyof Formulae (a2-r-1) and (a2-r-3) to (a2-r-7), or a —SO₂-containingcyclic group represented by any of formulae (a5-r-1) to (a5-r-4); R″¹⁰³represents an aromatic cyclic group which may have a substituent, analiphatic cyclic group which may have a substituent, or a chain-likealkenyl group which may have a substituent;

V″¹⁰¹ represents a single bond, an alkylene group having 1 to 4 carbonatoms or a fluorinated alkylene group having 1 to 4 carbon atoms; R¹⁰²represents a fluorine atom or a fluorinated alkyl group having 1 to 5carbon atoms; each v″ independently represents an integer of 0 to 3;each q″ independently represents an integer of 0 to 20; and n″represents 0 or 1.

As the aliphatic cyclic group for R″¹⁰¹, R″¹⁰² and R″¹⁰³ which may havea substituent, the same groups as the cyclic aliphatic hydrocarbon groupfor R¹⁰¹ in the aforementioned formula (b1-1-an1) are preferable.Examples of the substituent include the same substituents as thosedescribed above for the cyclic aliphatic hydrocarbon group for R¹⁰¹ inthe aforementioned formula (b1-1-an1).

As the aromatic cyclic group for R″¹⁰³ which may have a substituent, thesame groups as the aromatic hydrocarbon group for the cyclic hydrocarbongroup represented by R¹⁰¹ in the aforementioned formula (b1-1-an1) ispreferable. Examples of the substituent include the same substituents asthose described above for the aromatic hydrocarbon group for R¹⁰¹ in theaforementioned formula (b1-1-an1).

As the chain alkyl group for R″¹⁰¹ which may have a substituent, thesame chain alkyl groups as those described above for R¹⁰¹ in theaforementioned formula (b1-1-an1) are preferable.

As the chain alkenyl group for R″¹⁰³ which may have a substituent, thesame chain alkenyl groups as those described above for R¹⁰¹ in theaforementioned formula (b1-1-an1) are preferable.

Anion Represented by General Formula (b1-1-an2)

In formula (b1-1-an2), R¹⁰⁴ and R¹⁰⁵ each independently represents acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent, and is the same as defined for R¹⁰¹ in formula(b1-1-an1). R¹⁰⁴ and R¹⁰⁵ may be mutually bonded to form a ring.

As R¹⁰⁴ and R¹⁰⁵, a chain-like alkyl group which may have a substituentis preferable, and a linear or branched alkyl group or a linear orbranched fluorinated alkyl group is more preferable.

The chain-like alkyl group preferably has 1 to 10 carbon atoms, morepreferably 1 to 7 carbon atoms, and still more preferably 1 to 3 carbonatoms. The smaller the number of carbon atoms of the chain-like alkylgroup for R¹⁰⁴ and R¹⁰⁵, the more the solubility in a resist solvent isimproved. Further, in the chain alkyl group for R¹⁰⁴ and R¹⁰⁵, thelarger the number of hydrogen atoms being substituted with fluorineatom(s), the acid strength becomes stronger, and the transparency to ahigh energy beam having a wavelength of no more than 250 nm or electronbeam may be improved.

The fluorination ratio of the chain-like alkyl group is preferably from70 to 100%, more preferably from 90 to 100%, and it is particularlydesirable that the chain-like alkyl group be a perfluoroalkyl group inwhich all hydrogen atoms are substituted with fluorine atoms.

In formula (b1-1-an2), V¹⁰² and V¹⁰³ each independently represents asingle bond, an alkylene group or a fluorinated alkylene group, and isthe same as defined for V¹⁰¹ in formula (b1-1-an1).

In formula (b1-1-an2), L¹⁰¹ and L¹⁰² each independently represents asingle bond or an oxygen atom.

Anion Represented by General Formula (b1-1-an3)

In formula (b1-1-an3), R¹⁰⁶ to R¹⁰⁸ each independently represents acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent, and is the same as defined for R¹⁰¹ in formula(b1-1-an1).

In formula (b1-1-an3), L¹⁰³ to L¹⁰⁵ each independently represents asingle bond, —CO— or —SO₂—.

In the aforementioned formula (b1-1), X⁻ may be R¹⁰⁹—SO₃—. R¹⁰⁹represents a cyclic group which may have a substituent, a chain alkylgroup which may have a substituent, or a chain alkenyl group which mayhave a substituent, and is the same as defined for R¹⁰¹ in theaforementioned formula (b1-1-an1). However, in R¹⁰⁹, the carbon atomadjacent to the S atom has a fluorine atom bonded thereto.

Alternatively, in the aforementioned formula (b1-1), X⁻ may be a halogenanion. Examples of the halogen anion include a fluoride ion, a chlorideion, a bromide ion and an iodide ion.

Among these examples, as the anion moiety of the component (B1), ananion represented by general formula (b1-1-an1) is preferable. Amongthese, an anion represented by any one of the aforementioned generalformulae (an-1) to (an-3) is more preferable, and an anion representedby the aforementioned general formula (an-1) or (an-2) is morepreferable, and an anion represented by the aforementioned generalformula (an-1) is still more preferable.

As the component (B1), 1 kind of these acid generators may be usedalone, or 2 or more kinds may be used in combination.

In the present embodiment, as the component (B1), a compound representedby general formula (b1-10) shown below is most preferable.

In the formula, R¹⁰¹, Y¹⁰¹, V¹⁰¹ and R¹⁰² are the same as defined forR¹⁰¹, Y¹⁰¹, V¹⁰¹ and R¹⁰² in the aforementioned formula (b1-1-an1),respectively; R^(b10), R^(b20), R^(b30), n_(b1), n_(b2) and n_(b3) arethe same as defined for R^(b10), R^(b20), R^(b30), n_(b1), n_(b2) andn_(b3) in the aforementioned formula (b1-1), respectively.

Specific examples of preferable component (B1) are shown below.

In the resist composition of the present embodiment, as the component(B1), one kind of compound may be used, or two or more kinds ofcompounds may be used in combination.

In the resist composition of the present embodiment, the amount of thecomponent (B1) relative to 100 parts by weight of the component (A) ispreferably within a range from 0.5 to 7 parts by weight, more preferably1 to 4 parts by weight, and still more preferably 1 to 3 parts byweight.

When the amount of the component (B1) is within the above-mentionedrange, formation of a resist pattern can be satisfactorily performed.Further, by virtue of the above-mentioned range, when each of thecomponents are dissolved in an organic solvent, a homogeneous solutionmay be more reliably obtained and the storage stability of the resistcomposition becomes satisfactory. Furthermore, when the amount of thecomponent (B1) is at least as large as the lower limit of theabove-mentioned preferable range, the light transmittance of the resistfilm may be improved, so as to improve the sensitivity.

Component (B2)

The resist composition of the present embodiment may contain an acidgenerator other than the component (B1) (hereafter, referred to as“component (B2)”), as long as the effects of the present invention arenot impaired.

As the component (B2), there is no particular limitation, and any of theknown acid generators used in conventional chemically amplified resistcompositions may be used.

Examples of these acid generators are numerous, and include onium saltacid generators such as iodonium salts and sulfonium salts; oximesulfonate acid generators; diazomethane acid generators such as bisalkylor bisaryl sulfonyl diazomethanes and poly(bis-sulfonyl)diazomethanes;nitrobenzylsulfonate acid generators; iminosulfonate acid generators;and disulfone acid generators.

As the onium salt acid generator, a compound represented by generalformula (b-1) below (hereafter, sometimes referred to as “component(b-1)”), a compound represented by general formula (b-2) below(hereafter, sometimes referred to as “component (b-2)”) or a compoundrepresented by general formula (b-3) below (hereafter, sometimesreferred to as “component (b-3)”) may be mentioned.

In the formulae, R¹⁰¹ and R¹⁰⁴ to R¹⁰⁸ each independently represents acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent, provided that R¹⁰⁴ and R¹⁰⁵ may be mutually bondedto form a ring;

R¹⁰² represents a fluorine atom or a fluorinated alkyl group of 1 to 5carbon atoms; Y¹⁰¹ represents a single bond or a divalent linking groupcontaining an oxygen atom; V¹⁰¹ to V¹⁰³ each independently represents asingle bond, an alkylene group or a fluorinated alkylene group; L¹⁰¹ andL¹⁰² each independently represents a single bond or an oxygen atom; L¹⁰³to L¹⁰⁵ each independently represents a single bond, —CO— or —SO₂—; mrepresents an integer of 1 or more; and M′^(m+) represents an m-valentonium cation.

{Anion Moiety}

The anion moiety of the component (b-1) is the same as defined for theanion moiety represented by the aforementioned general formula(b1-1-an1).

The anion moiety of the component (b-2) is the same as defined for theanion moiety represented by the aforementioned general formula(b1-1-an2).

The anion moiety of the component (b-3) is the same as defined for theanion moiety represented by the aforementioned general formula(b1-1-an3).

{Cation Moiety}

In formulae (b-1), (b-2) and (b-3), M′^(m+) represents an onium cationhaving a valency of m (provided that cations which fall under thedefinition of the cation moiety represented by the aforementionedgeneral formula (b1-1) are excluded. Among these, a sulfonium cation ora iodonium cation is preferable.

m represents an integer of 1 or more.

Preferable examples of the cation moiety ((M′^(m+))_(1/m)) include anorganic cation represented by any of general formulae (ca-1) to (ca-4)shown below.

In the formulae, R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² each independentlyrepresents an aryl group which may have a substituent, an alkyl groupwhich may have a substituent, or an alkenyl group which may have asubstituent. R²⁰¹ to R²⁰³, R²⁰⁶ and R²⁰⁷, and R²¹¹ and R²¹² may bemutually bonded to form a ring with the sulfur atom. R²⁰⁸ and R²⁰⁹ eachindependently represents a hydrogen atom or an alkyl group of 1 to 5carbon atoms. R²¹⁰ represents an aryl group which may have asubstituent, an alkyl group which may have a substituent, an alkenylgroup which may have a substituent, or an —SO₂— containing cyclic groupwhich may have a substituent. L²⁰¹ represents —C(═O)— or —C(═O)—O—. EachY²⁰¹ independently represents an arylene group, an alkylene group or analkenylene group. x represents 1 or 2. W²⁰¹ represents an (x+1) valentlinking group.

In formulae (ca-1) to (ca-4), as the aryl group for R²⁰¹ to R²⁰⁷, R²¹¹and R²¹², an unsubstituted aryl group of 6 to 20 carbon atoms can bementioned, and a phenyl group or a naphthyl group is preferable.

The alkyl group for R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² is preferably achain-like or cyclic alkyl group having 1 to 30 carbon atoms.

The alkenyl group for R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² preferably has 2 to 10carbon atoms.

Specific examples of the substituent which R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹²may have include an alkyl group, a halogen atom, a halogenated alkylgroup, a carbonyl group, a cyano group, an amino group, an aryl group,and groups represented by the aforementioned general formulae (ca-r-1)to (ca-r-7).

In general formulae (ca-1) to (ca-4), in the case where R²⁰¹ to R²⁰³,R²⁰⁶, R²⁰⁷, R²¹¹ and R²¹² are mutually bonded to form a ring with thesulfur atom, these groups may be mutually bonded via a hetero atom suchas a sulfur atom, an oxygen atom or a nitrogen atom, or a functionalgroup such as a carbonyl group, —SO—, —SO₂—, —SO₃—, —COO—, —CONH— or—N(R_(N))— (wherein R_(N) represents an alkyl group of 1 to 5 carbonatoms). The ring containing the sulfur atom in the skeleton thereof ispreferably a 3 to 10-membered ring, and most preferably a 5 to7-membered ring. Specific examples of the ring formed include athiophene ring, a thiazole ring, a benzothiophene ring, a thianthrenering, a benzothiophene ring, a dibenzothiophene ring, a 9H-thioxanthenering, a thioxanthone ring, a phenoxathiin ring, a tetrahydrothiopheniumring, and a tetrahydrothiopyranium ring.

R²⁰⁸ and R²⁰⁹ each independently represents a hydrogen atom or an alkylgroup of 1 to 5 carbon atoms, preferably a hydrogen atom or an alkylgroup of 1 to 3 carbon atoms, and when R²⁰⁸ and R²⁰⁹ each represents analkyl group, R²⁰⁸ and R²⁰⁹ may be mutually bonded to form a ring.

R²¹⁰ represents an aryl group which may have a substituent, an alkylgroup which may have a substituent, an alkenyl group which may have asubstituent, or an —SO₂— containing cyclic group which may have asubstituent.

Examples of the aryl group for R²¹⁰ include an unsubstituted aryl groupof 6 to 20 carbon atoms, and a phenyl group or a naphthyl group ispreferable.

As the alkyl group for R²¹⁰, a chain-like or cyclic alkyl group having 1to 30 carbon atoms is preferable.

The alkenyl group for R²¹⁰ preferably has 2 to 10 carbon atoms.

As the —SO₂— containing cyclic group for R²¹⁰ which may have asubstituent, an “—SO₂— containing polycyclic group” is preferable, and agroup represented by the aforementioned general formula (a5-r-1) is morepreferable.

Each Y²⁰¹ independently represents an arylene group, an alkylene groupor an alkenylene group.

Examples of the arylene group for Y²⁰¹ include groups in which onehydrogen atom has been removed from an aryl group given as an example ofthe aromatic hydrocarbon group for R¹⁰¹ in the aforementioned formula(b1-1-an1).

Examples of the alkylene group and alkenylene group for Y²⁰¹ includegroups in which one hydrogen atom has been removed from the chain-likealkyl group or the chain-like alkenyl group given as an example of R¹⁰¹in the aforementioned formula (b1-1-an1).

In the formula (ca-4), x represents 1 or 2.

W²⁰¹ represents a linking group having a valency of (x+1), i.e., adivalent or trivalent linking group.

As the divalent linking group for W²⁰¹, a divalent hydrocarbon groupwhich may have a substituent is preferable, and as examples thereof, thesame hydrocarbon groups (which may have a substituent) as thosedescribed above for Ya²¹ in the general formula (a2-1) can be mentioned.The divalent linking group for W²⁰¹ may be linear, branched or cyclic,and cyclic is more preferable. Among these, an arylene group having twocarbonyl groups, each bonded to the terminal thereof is preferable.Examples of the arylene group include a phenylene group and anaphthylene group, and a phenylene group is particularly desirable.

As the trivalent linking group for W²⁰¹, a group in which one hydrogenatom has been removed from the aforementioned divalent linking group forW²⁰¹ and a group in which the divalent linking group has been bonded toanother divalent linking group can be mentioned. The trivalent linkinggroup for W²⁰¹ is preferably a group in which 2 carbonyl groups arebonded to an arylene group.

Specific examples of preferable cations represented by formula (ca-1)include cations represented by chemical formulae (ca-1-1) to (ca-1-70)shown below.

In the formulae, g1, g2 and g2 represent recurring numbers, wherein g1is an integer of 1 to 5, g2 is an integer of 0 to 20, and g3 is aninteger of 0 to 20.

In the formulae, R″²⁰¹ represents a hydrogen atom or a substituent, andas the substituent, the same groups as those described above forsubstituting R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹² can be mentioned.

Specific examples of preferable cations represented by the formula(ca-2) include a diphenyliodonium cation and abis(4-tert-butylphenyl)iodonium cation.

Specific examples of preferable cations represented by formula (ca-3)include cations represented by formulae (ca-3-1) to (ca-3-6) shownbelow.

Specific examples of preferable cations represented by formula (ca-4)include cations represented by formulae (ca-4-1) and (ca-4-2) shownbelow.

Among these examples, as the cation moiety ((M′^(m+))_(1/m)), a cationrepresented by general formula (ca-1) is preferable.

In the resist composition of the present embodiment, as the component(B2), one kind of compound may be used, or two or more kinds ofcompounds may be used in combination.

When the resist composition contains the component (B2), the amount ofthe component (B2) relative to 100 parts by weight of the component (A)is preferably less than 50 parts by weight, more preferably 1 to 20parts by weight, and still more preferably 1 to 10 parts by weight.

When the amount of the component (B2) is within the above-mentionedrange, formation of pattern satisfactorily occurs. Further, by virtue ofthe above-mentioned range, when each of the components are dissolved inan organic solvent, a homogeneous solution may be more reliably obtainedand the storage stability of the resist composition becomessatisfactory.

<Other Components>

The resist composition of the present embodiment may contain, inaddition to the aforementioned components (A) and (B), any otheroptional components. Examples of the other components include thecomponents (D), (E), (F) and (S) described below.

«Basic Component (D)»

The resist composition of the present embodiment may contain, inaddition to the aforementioned components (A) and (B), a basic component(component (D)) which is capable of trapping acid generated from thecomponent (B) upon exposure (i.e., capable of controlling diffusion ofacid). The component (D) functions as an acid diffusion control agent,i.e., a quencher which traps the acid generated in the resistcomposition upon exposure.

Examples of the component (D) include a photodecomposable base (D1)(hereafter, referred to as “component (D1)”) which is decomposed uponexposure and then loses the ability of controlling of acid diffusion,and a nitrogen-containing organic compound (D2) (hereafter, referred toas “component (D2)”) which does not fall under the definition ofcomponent (D1).

Component (D1)

When a resist pattern is formed using a resist composition containingthe component (D1), the contrast between exposed portions and unexposedportions of the resist film is further improved.

The component (D1) is not particularly limited, as long as it isdecomposed upon exposure and then loses the ability of controlling ofacid diffusion. As the component (D1), at least one compound selectedfrom the group consisting of a compound represented by general formula(d1-1) shown below (hereafter, referred to as “component (d1-1)”), acompound represented by general formula (d1-2) shown below (hereafter,referred to as “component (d1-2)”) and a compound represented by generalformula (d1-3) shown below (hereafter, referred to as “component(d1-3)”) is preferably used.

At exposed portions of the resist film, the components (d1-1) to (d1-3)are decomposed and then lose the ability of controlling of aciddiffusion (i.e., basicity), and therefore the components (d1-1) to(d1-3) cannot function as a quencher, whereas at unexposed portions ofthe resist film, the components (d1-1) to (d1-3) functions as aquencher.

In the formulae, Rd¹ to Rd⁴ represent a cyclic group which may have asubstituent, a chain alkyl group which may have a substituent or a chainalkenyl group which may have a substituent, provided that, the carbonatom adjacent to the sulfur atom within the Rd² in the formula (d1-2)has no fluorine atom bonded thereto; Yd¹ represents a single bond or adivalent linking group; m represents an integer of 1 or more; and eachM^(m+) independently represents an organic cation having a valency of m.

{Component (d1-1)}

Anion Moiety

In formula (d1-1), Rd¹ represents a cyclic group which may have asubstituent, a chain alkyl group which may have a substituent or a chainalkenyl group which may have a substituent, and is the same groups asthose defined above for R′²⁰¹.

Among these, as the group for Rd¹, an aromatic hydrocarbon group whichmay have a substituent, an aliphatic cyclic group which may have asubstituent and a chain-like alkyl group which may have a substituentare preferable. Examples of the substituent for these groups include ahydroxy group, an oxo group, an alkyl group, an aryl group, a fluorineatom, a fluorinated alkyl group, a lactone-containing cyclic grouprepresented by any one of the aforementioned formulae (a2-r-1) to(a2-r-7), an ether bond, an ester bond, and a combination thereof. Inthe case where an ether bond or an ester bond is included as thesubstituent, the substituent may be bonded via an alkylene group, and alinking group represented by any one of the aforementioned formulae(y-a1-1) to (y-a1-5) is preferable as the substituent.

Preferable examples of the aromatic hydrocarbon group include a phenylgroup, a naphthyl group, and a polycyclic structure containing abicyclooctane skeleton (a polycyclic structure constituted of abicyclooctane skeleton and a ring structure other than bicyclooctane).

Examples of the aliphatic cyclic group include groups in which one ormore hydrogen atoms have been removed from a polycycloalkane such asadamantane, norbomane, isobornane, tricyclodecane or tetracyclododecane.

The chain-like alkyl group preferably has 1 to 10 carbon atoms, andspecific examples thereof include a linear alkyl group such as a methylgroup, an ethyl group, a propyl group, a butyl group, a pentyl group, ahexyl group, a heptyl group, an octyl group, a nonyl or a decyl group,and a branched alkyl group such as a 1-methylethyl group, a1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a3-methylpentyl group or a 4-methylpentyl group.

In the case where the chain-like alkyl group is a fluorinated alkylgroup having a fluorine atom or a fluorinated alkyl group, thefluorinated alkyl group preferably has 1 to 11 carbon atoms, morepreferably 1 to 8 carbon atoms, and still more preferably 1 to 4 carbonatoms. The fluorinated alkyl group may contain an atom other thanfluorine. Examples of the atom other than fluorine include an oxygenatom, a sulfur atom and a nitrogen atom.

As Rd¹, a fluorinated alkyl group in which part or all of the hydrogenatoms constituting a linear alkyl group have been substituted withfluorine atom(s) is preferable, and a fluorinated alkyl group in whichall of the hydrogen atoms constituting a linear alkyl group have beensubstituted with fluorine atoms (i.e., a linear perfluoroalkyl group) isparticularly desirable.

Specific examples of preferable anion moieties for the component (d1-1)are shown below.

Cation Moiety

In formula (d1-1), M^(m+) represents an organic cation having a valencyof m.

As the organic cation for M^(m+), for example, the same cation moietiesas those represented by the aforementioned formulae (ca-1) to (ca-4) arepreferable, cation moieties represented by the aforementioned generalformulae (ca-1) is preferable, and cation moieties represented by theaforementioned formulae (ca-1-1) to (ca-1-70) are still more preferable.

As the component (d1-1), one kind of compound may be used, or two ormore kinds of compounds may be used in combination.

{Component (d1-2)}

Anion Moiety

In formula (d1-2), Rd² represents a cyclic group which may have asubstituent, a chain alkyl group which may have a substituent or a chainalkenyl group which may have a substituent, and is the same groups asthose defined above for R′²⁰¹.

However, the carbon atom adjacent to the sulfur atom within the Rd² hasno fluorine atom bonded thereto. As a result, the anion of the component(d1-2) becomes an appropriately weak acid anion, thereby improving thequenching ability of the component (D).

As Rd², a chain-like alkyl group which may have a substituent or analiphatic cyclic group which may have a substituent is preferable. Thechain-like alkyl group preferably has 1 to 10 carbon atoms, and morepreferably 3 to 10 carbon atoms. As the aliphatic cyclic group, a groupin which one or more hydrogen atoms have been removed from adamantane,norbomane, isobornane, tricyclodecane, tetracyclododecane or camphor(which may have a substituent) is more preferable.

The hydrocarbon group for Rd² may have a substituent. As thesubstituent, the same groups as those described above for substitutingthe hydrocarbon group (e.g., aromatic hydrocarbon group, aliphaticcyclic group, chain-like alkyl group) for Rd¹ in the formula (d1-1) canbe mentioned.

Specific examples of preferable anion moieties for the component (d1-2)are shown below.

Cation Moiety

In formula (d1-2), M^(m+) is an organic cation having a valency of m,and is the same as defined for M^(m+) in the aforementioned formula(d1-1).

As the component (d1-2), one type of compound may be used, or two ormore types of compounds may be used in combination.

{Component (d1-3)}

Anion Moiety

In formula (d1-3), Rd³ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R′²⁰¹, and a cyclic group containing afluorine atom, a chain alkyl group or a chain alkenyl group ispreferable. Among these, a fluorinated alkyl group is preferable, andmore preferably the same fluorinated alkyl groups as those describedabove for Rd¹.

In formula (d1-3), Rd⁴ represents a cyclic group which may have asubstituent, a chain alkyl group which may have a substituent or a chainalkenyl group which may have a substituent, and is the same groups asthose defined above for R′²⁰¹.

Among these, an alkyl group which may have substituent, an alkoxy groupwhich may have substituent, an alkenyl group which may have substituentor a cyclic group which may have substituent is preferable.

The alkyl group for Rd⁴ is preferably a linear or branched alkyl groupof 1 to 5 carbon atoms, and specific examples include a methyl group, anethyl group, a propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a tert-butyl group, a pentyl group, an isopentyl group,and a neopentyl group. Part of the hydrogen atoms within the alkyl groupfor Rd⁴ may be substituted with a hydroxy group, a cyano group or thelike.

The alkoxy group for Rd⁴ is preferably an alkoxy group of 1 to 5 carbonatoms, and specific examples thereof include a methoxy group, an ethoxygroup, an n-propoxy group, an iso-propoxy group, an n-butoxy group and atert-butoxy group. Among these, a methoxy group and an ethoxy group arepreferable.

The alkenyl group for Rd⁴ is the same as defined for the alkenyl groupfor R′²⁰¹ and a vinyl group, a propenyl group (an allyl group), a1-methylpropenyl group or a 2-methylpropenyl group is preferable. Thesegroups may have an alkyl group of 1 to 5 carbon atoms or a halogenatedalkyl group of 1 to 5 carbon atoms as a substituent.

As the cyclic group for Rd⁴, the same groups as those described abovefor R′²⁰¹ may be mentioned. Among these, as the cyclic group, analicyclic group (e.g., a group in which one or more hydrogen atoms havebeen removed from a cycloalkane such as cyclopentane, cyclohexane,adamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane) or an aromatic group (e.g., a phenyl group or anaphthyl group) is preferable. When Rd⁴ is an alicyclic group, theresist composition can be satisfactorily dissolved in an organicsolvent, thereby improving the lithography properties. Alternatively,when Rd⁴ is an aromatic group, the resist composition exhibits anexcellent photoabsorption efficiency in a lithography process using EUVor the like as the exposure source, thereby resulting in the improvementof the sensitivity and the lithography properties.

In formula (d1-3), Yd¹ represents a single bond or a divalent linkinggroup.

The divalent linking group for Yd¹ is not particularly limited, andexamples thereof include a divalent hydrocarbon group (aliphatichydrocarbon group, or aromatic hydrocarbon group) which may have asubstituent and a divalent linking group containing a hetero atom. Thedivalent linking groups are the same as defined for the divalenthydrocarbon group which may have a substituent and the divalent linkinggroup containing a hetero atom explained above as the divalent linkinggroup for Ya²¹ in the aforementioned formula (a2-1).

As Yd¹, a carbonyl group, an ester bond, an amide bond, an alkylenegroup or a combination of these is preferable. As the alkylene group, alinear or branched alkylene group is more preferable, and a methylenegroup or an ethylene group is still more preferable.

Specific examples of preferable anion moieties for the component (d1-3)are shown below.

Cation Moiety

In formula (d1-3), M^(m+) is an organic cation having a valency of m,and is the same as defined for M^(m+) in the aforementioned formula(d1-1).

As the component (d1-3), one type of compound may be used, or two ormore types of compounds may be used in combination.

As the component (D1), one type of the aforementioned components (d1-1)to (d1-3), or at least two types of the aforementioned components (d1-1)to (d1-3) can be used in combination.

In the case where the resist composition contains the component (D1),the amount of the component (D1) relative to 100 parts by weight of thecomponent (A) is preferably within a range from 0.5 to 20 parts byweight, more preferably from 1 to 15 parts by weight, and still morepreferably from 5 to 10 parts by weight.

When the amount of the component (D1) is at least as large as the lowerlimit of the above-mentioned range, excellent lithography properties andexcellent resist pattern shape can be more reliably obtained. On theother hand, when the amount of the component (D1) is no more than theupper limit of the above-mentioned range, sensitivity can be maintainedat a satisfactory level, and through-put becomes excellent.

Production Method of Component (D1):

The production methods of the components (d1-1) and (d1-2) are notparticularly limited, and the components (d1-1) and (d1-2) can beproduced by conventional methods.

Further, the production method of the component (d1-3) is notparticularly limited, and the component (d1-3) can be produced in thesame manner as disclosed in US2012-0149916.

Component (D2)

The acid diffusion control component may contain a nitrogen-containingorganic compound (D2) (hereafter, referred to as component (D2)) whichdoes not fall under the definition of component (D1).

The component (D2) is not particularly limited, as long as it functionsas an acid diffusion control agent, and does not fall under thedefinition of the component (D1). As the component (D2), any of theconventionally known compounds may be selected for use. Among these, analiphatic amine is preferable, and a secondary aliphatic amine ortertiary aliphatic amine is more preferable.

An aliphatic amine is an amine having one or more aliphatic groups, andthe aliphatic groups preferably have 1 to 12 carbon atoms.

Examples of these aliphatic amines include amines in which at least onehydrogen atom of ammonia (NH₃) has been substituted with an alkyl groupor hydroxyalkyl group of no more than 12 carbon atoms (i.e., alkylaminesor alkylalcoholamines), and cyclic amines.

Specific examples of alkylamines and alkylalcoholamines includemonoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine,n-nonylamine, and n-decylamine; dialkylamines such as diethylamine,di-n-propylamine, di-n-heptylamine, di-n-octylamine, anddicyclohexylamine; trialkylamines such as trimethylamine, triethylamine,tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine,tri-n-pentylamine, tri-n-heptylamine, tri-n-octylamine,tri-n-nonylamine, tri-n-decylamine, and tri-n-dodecylamine; and alkylalcohol amines such as diethanolamine, triethanolamine,diisopropanolamine, triisopropanolamine, di-n-octanolamine, andtri-n-octanolamine. Among these, trialkylamines of 5 to 10 carbon atomsare preferable, and tri-n-pentylamine and tri-n-octylamine areparticularly desirable.

Examples of the cyclic amine include heterocyclic compounds containing anitrogen atom as a hetero atom. The heterocyclic compound may be amonocyclic compound (aliphatic monocyclic amine), or a polycycliccompound (aliphatic polycyclic amine).

Specific examples of the aliphatic monocyclic amine include piperidine,and piperazine.

The aliphatic polycyclic amine preferably has 6 to 10 carbon atoms, andspecific examples thereof include 1,5-diazabicyclo[4.3.0]-5-nonene,1,8-diazabicyclo[5.4.0]-7-undecene, hexamethylenetetramine, and1,4-diazabicyclo[2.2.2]octane.

Examples of other aliphatic amines includetris(2-methoxymethoxyethyl)amine, tris {2-(2-methoxyethoxy)ethyl}amine,tris {2-(2-methoxyethoxymethoxy)ethyl}amine, tris{2-(1-methoxyethoxy)ethyl}amine, tris {2-(1-ethoxyethoxy)ethyl}amine,tris {2-(1-ethoxypropoxy)ethyl}amine,tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine and triethanolaminetriacetate, and triethanolamine triacetate is preferable.

Further, as the component (D2), an aromatic amine may be used.

Examples of aromatic amines include 4-dimethylaminopyridine, pyrrole,indole, pyrazole, imidazole and derivatives thereof, as well astribenzylamine, 2,6-diisopropylaniline andN-tert-butoxycarbonylpyrrolidine.

As the component (D2), one kind of compound may be used, or two or morekinds of compounds may be used in combination.

When the resist composition contains the component (D2), the amount ofthe component (D2) is typically used in an amount within a range from0.01 to 5 parts by weight, relative to 100 parts by weight of thecomponent (A). When the amount of the component (D) is within theabove-mentioned range, the shape of the resist pattern and the postexposure stability of the latent image formed by the pattern-wiseexposure of the resist layer are improved.

«At Least One Compound (E) Selected from the Group Consisting of anOrganic Carboxylic Acid, or a Phosphorus Oxo Acid or Derivative Thereof»

In the resist composition of the present embodiment, for preventing anydeterioration in sensitivity, and improving the resist pattern shape andthe post exposure stability of the latent image formed by thepattern-wise exposure of the resist layer, at least one compound (E)(hereafter referred to as the component (E)) selected from the groupconsisting of an organic carboxylic acid, or a phosphorus oxo acid orderivative thereof may be added.

Examples of suitable organic carboxylic acids include acetic acid,malonic acid, citric acid, malic acid, succinic acid, benzoic acid, andsalicylic acid.

Examples of phosphorus oxo acids include phosphoric acid, phosphonicacid and phosphinic acid. Among these, phosphonic acid is particularlydesirable.

Examples of oxo acid derivatives include esters in which a hydrogen atomwithin the above-mentioned oxo acids is substituted with a hydrocarbongroup. Examples of the hydrocarbon group include an alkyl group of 1 to5 carbon atoms and an aryl group of 6 to 15 carbon atoms.

Examples of phosphoric acid derivatives include phosphoric acid esterssuch as di-n-butyl phosphate and diphenyl phosphate.

Examples of phosphonic acid derivatives include phosphonic acid esterssuch as dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonicacid, diphenyl phosphonate and dibenzyl phosphonate.

Examples of phosphinic acid derivatives include phosphinic acid estersand phenylphosphinic acid.

In the resist composition of the present embodiment, as the component(E), one kind of compound may be used, or two or more kinds of compoundsmay be used in combination.

When the resist composition contains the component (E), the amount ofthe component (E) is typically used in an amount within a range from0.01 to 5 parts by weight, relative to 100 parts by weight of thecomponent (A).

«Fluorine Additive (F)»

In the present embodiment, the resist composition may further include afluorine additive (hereafter, referred to as “component (F)”) forimparting water repellency to the resist film, or improving lithographyproperties.

As the component (F), for example, a fluorine-containing polymericcompound described in Japanese Unexamined Patent Application, FirstPublication No. 2010-002870, Japanese Unexamined Patent Application,First Publication No. 2010-032994, Japanese Unexamined PatentApplication, First Publication No. 2010-277043, Japanese UnexaminedPatent Application, First Publication No. 2011-13569, and JapaneseUnexamined Patent Application, First Publication No. 2011-128226 can beused.

Specific examples of the component (F) include polymers having astructural unit (f1) represented by general formula (f1-1) shown below.As the polymer, a polymer (homopolymer) consisting of a structural unit(f1) represented by formula (f1-1) shown below; a copolymer of thestructural unit (f1) and the aforementioned structural unit (a1); and acopolymer of the structural unit (f1), a structural unit derived fromacrylic acid or methacrylic acid and the aforementioned structural unit(a1) are preferable. As the structural unit (a1) to be copolymerizedwith the structural unit (f1), a structural unit derived from1-ethyl-1-cyclooctyl (meth)acrylate or a structural unit derived from1-methyl-1-adamantyl (meth)acrylate is preferable.

In the formula, R is the same as defined above; Rf¹⁰² and Rf¹⁰³ eachindependently represents a hydrogen atom, a halogen atom, an alkyl groupof 1 to 5 carbon atoms, or a halogenated alkyl group of 1 to 5 carbonatoms, provided that Rf¹⁰² and Rf¹⁰³ may be the same or different; nf¹represents an integer of 1 to 5; and Rf¹⁰¹ represents an organic groupcontaining a fluorine atom.

In formula (f1-1), R bonded to the carbon atom on the α-position is thesame as defined above. As R, a hydrogen atom or a methyl group ispreferable.

In formula (f1-1), examples of the halogen atom for Rf¹⁰² and Rf¹⁰³include a fluorine atom, a chlorine atom, a bromine atom and an iodineatom, and a fluorine atom is particularly desirable. Examples of thealkyl group of 1 to 5 carbon atoms for Rf¹⁰² and Rf¹⁰³ include the samealkyl group of 1 to 5 carbon atoms as those described above for R, and amethyl group or an ethyl group is preferable. Specific examples of thehalogenated alkyl group of 1 to 5 carbon atoms represented by Rf¹⁰² orRf¹⁰³ include groups in which part or all of the hydrogen atoms of theaforementioned alkyl groups of 1 to 5 carbon atoms have been substitutedwith halogen atoms.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom, and a fluorine atom is particularlydesirable. Among these examples, as Rf¹⁰² and Rf¹⁰³, a hydrogen atom, afluorine atom or an alkyl group of 1 to 5 carbon atoms is preferable,and a hydrogen atom, a fluorine atom, a methyl group or an ethyl groupis more preferable.

In formula (f1-1), nf¹ represents an integer of 1 to 5, preferably aninteger of 1 to 3, and more preferably 1 or 2.

In formula (f1-1), Rf¹⁰¹ represents an organic group containing afluorine atom, and is preferably a hydrocarbon group containing afluorine atom.

The hydrocarbon group containing a fluorine atom may be linear, branchedor cyclic, and preferably has 1 to 20 carbon atoms, more preferably 1 to15 carbon atoms, and most preferably 1 to 10 carbon atoms.

It is preferable that the hydrocarbon group having a fluorine atom has25% or more of the hydrogen atoms within the hydrocarbon groupfluorinated, more preferably 50% or more, and most preferably 60% ormore, as the hydrophobicity of the resist film during immersion exposureis enhanced.

Among these, as Rf¹⁰¹, a fluorinated hydrocarbon group of 1 to 6 carbonatoms is preferable, and a trifluoromethyl group, —CH₂—CF₃,—CH₂—CF₂—CF₃, —CH(CF₃)₂, —CH₂—CH₂—CF₃, and —CH₂—CH₂—CF₂—CF₂—CF₂—CF₃ aremost preferable.

The weight average molecular weight (Mw) (the polystyrene equivalentvalue determined by gel permeation chromatography) of the component (F)is preferably 1,000 to 50,000, more preferably 5,000 to 40,000, and mostpreferably 10,000 to 30,000. When the weight average molecular weight(Mw) is no more than the upper limit of the above-mentioned range, theresist may exhibit satisfactory solubility in a resist solvent. On theother hand, when the weight average molecular weight (Mw) is at least aslarge as the lower limit of the above-mentioned range, the waterrepellency of the resist film may become satisfactory.

Further, the dispersity (Mw/Mn) of the component (F) is preferably 1.0to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5.

In the resist composition of the present embodiment, as the component(F), one kind of compound may be used, or two or more kinds of compoundsmay be used in combination.

When the resist composition contains the component (F), the component(F) is used in an amount within a range from 0.5 to 10 parts by weight,relative to 100 parts by weight of the component (A).

«Organic Solvent (S)»

The resist composition of the present embodiment may be prepared bydissolving the resist materials for the resist composition in an organicsolvent (hereafter, referred to as “component (S)”).

The component (S) may be any organic solvent which can dissolve therespective components to give a homogeneous solution, and any organicsolvent can be appropriately selected from those which have beenconventionally known as solvents for a chemically amplified resistcomposition.

Examples thereof include lactones such as γ-butyrolactone; ketones suchas acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone,methyl isopentyl ketone, and 2-heptanone; polyhydric alcohols, such asethylene glycol, diethylene glycol, propylene glycol and dipropyleneglycol; compounds having an ester bond, such as ethylene glycolmonoacetate, diethylene glycol monoacetate, propylene glycolmonoacetate, and dipropylene glycol monoacetate; polyhydric alcoholderivatives including compounds having an ether bond, such as amonoalkylether (e.g., monomethylether, monoethylether, monopropyletheror monobutylether) or monophenylether of any of these polyhydricalcohols or compounds having an ester bond (among these, propyleneglycol monomethyl ether acetate (PGMEA) and propylene glycol monomethylether (PGME) are preferable); cyclic ethers such as dioxane; esters suchas methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate,butyl acetate, methyl pyruvate, ethyl pyruvate, methylmethoxypropionate, and ethyl ethoxypropionate; aromatic organic solventssuch as anisole, ethylbenzylether, cresylmethylether, diphenylether,dibenzylether, phenetole, butylphenylether, ethylbenzene,diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymeneand mesitylene; and dimethylsulfoxide (DMSO).

In the resist composition of the present embodiment, as the component(S), one kind of solvent may be used, or two or more kinds of compoundsmay be used as a mixed solvent. Among these examples, PGMEA, PGME,γ-butyrolactone, EL and cyclohexanone are preferable.

Further, as the component (S), a mixed solvent obtained by mixing PGMEAwith a polar solvent is preferable.

The mixing ratio (weight ratio) of the mixed solvent can beappropriately determined, taking into consideration the compatibility ofthe PGMEA with the polar solvent, but is preferably in the range of 1:9to 9:1, more preferably from 2:8 to 8:2.

Specifically, when EL or cyclohexanone is mixed as the polar solvent,the PGMEA:EL or cyclohexanone weight ratio is preferably from 1:9 to9:1, and more preferably from 2:8 to 8:2. Alternatively, when PGME ismixed as the polar solvent, the PGMEA:PGME weight ratio is preferablyfrom 1:9 to 9:1, more preferably from 2:8 to 8:2, and still morepreferably 3:7 to 7:3. Furthermore, a mixed solvent of PGMEA, PGME andcyclohexanone is also preferable.

Further, as the component (S), a mixed solvent of at least one of PGMEAand EL with γ-butyrolactone is also preferable. The mixing ratio(former:latter) of such a mixed solvent is preferably from 70:30 to95:5.

The amount of the component (S) is not particularly limited, and isappropriately adjusted to a concentration which enables coating of acoating solution to a substrate. In general, the component (S) is usedin an amount such that the solid content of the resist compositionbecomes within the range from 0.1 to 20% by weight, and preferably from0.2 to 15% by weight.

If desired, other miscible additives can also be added to the resistcomposition of the present invention. Examples of such miscibleadditives include additive resins for improving the performance of theresist film, dissolution inhibitors, plasticizers, stabilizers,colorants, halation prevention agents, and dyes.

After dissolving the resist materials in the organic solvent (S), theresist composition of the present embodiment may have impurities or thelike removed by using a polyimide porous film, a polyamide-imide porousfilm, or the like. For example, the resist composition may be subjectedto filtration using a filter formed of a polyimide porous membrane, afilter formed of a polyamide-imide porous film, or a filter formed of apolyimide porous membrane and a polyamide-imide porous film. Examples ofthe polyimide porous membrane and the polyamide-imide porous filminclude those described in Japanese Unexamined Patent Application, FirstPublication No. 2016-155121.

In the resist composition according to the present embodiment describedabove, a resin component having an acid dissociable group having a5-membered aliphatic monocyclic structure and a carbon-carbonunsaturated bond is used in combination with an acid generator having acation moiety containing a triphenylsulfonium in which a sulfonyl group(an electron-withdrawing group) linked to a cyclic group is bonded as asubstituent. It is presumed that, by the synergistic effect of thecombination of the resin component and the acid generator, it becomespossible to achieve sensitivity and resolution performance, as well asreduction of roughness, which were conventionally difficult to achievesimultaneously. According to the resist composition of the presentembodiment, in the formation of a resist pattern, sensitivity may beenhanced, and a resist pattern exhibiting good lithography properties(resolution performance, reduction of roughness, and the like) andhaving a good shape, e.g., high rectangularity, may be formed.

(Method of Forming a Resist Pattern)

The method of forming a resist pattern according to the second aspect ofthe present invention includes: using a resist composition according tothe first aspect to form a resist film on a substrate; exposing theresist film; and developing the exposed resist film to form a resistpattern.

The method for forming a resist pattern according to the presentembodiment can be performed, for example, as follows.

Firstly, a resist composition of the first aspect is applied to asubstrate using a spinner or the like, and a bake treatment (postapplied bake (PAB)) is conducted at a temperature of 80 to 150° C. for40 to 120 seconds, preferably 60 to 90 seconds, to form a resist film.

Following selective exposure of the thus formed resist film, either byexposure through a mask having a predetermined pattern formed thereon(mask pattern) using an exposure apparatus such an electron beamlithography apparatus or an EUV exposure apparatus, or by patterning viadirect irradiation with an electron beam without using a mask pattern,baking treatment (post exposure baking (PEB)) is conducted undertemperature conditions of 80 to 150° C. for 40 to 120 seconds, andpreferably 60 to 90 seconds.

Next, the resist film is subjected to a developing treatment. Thedeveloping treatment is conducted using an alkali developing solution inthe case of an alkali developing process, and a developing solutioncontaining an organic solvent (organic developing solution) in the caseof a solvent developing process.

After the developing treatment, it is preferable to conduct a rinsetreatment. The rinse treatment is preferably conducted using pure waterin the case of an alkali developing process, and a rinse solutioncontaining an organic solvent in the case of a solvent developingprocess.

In the case of a solvent developing process, after the developingtreatment or the rinsing, the developing solution or the rinse liquidremaining on the pattern can be removed by a treatment using asupercritical fluid.

After the developing treatment or the rinse treatment, drying isconducted. If desired, bake treatment (post bake) can be conductedfollowing the developing.

In this manner, a resist pattern can be formed.

The substrate is not specifically limited and a conventionally knownsubstrate can be used. For example, substrates for electroniccomponents, and such substrates having wiring patterns formed thereoncan be used. Specific examples of the material of the substrate includemetals such as silicon wafer, copper, chromium, iron and aluminum; andglass. Suitable materials for the wiring pattern include copper,aluminum, nickel, and gold.

Further, as the substrate, any one of the above-mentioned substratesprovided with an inorganic and/or organic film on the surface thereofmay be used. As the inorganic film, an inorganic antireflection film(inorganic BARC) can be used. As the organic film, an organicantireflection film (organic BARC) and an organic film such as alower-layer organic film used in a multilayer resist method can be used.

Here, a “multilayer resist method” is method in which at least one layerof an organic film (lower-layer organic film) and at least one layer ofa resist film (upper resist film) are provided on a substrate, and aresist pattern formed on the upper resist film is used as a mask toconduct patterning of the lower-layer organic film. This method isconsidered as being capable of forming a pattern with a high aspectratio. More specifically, in the multilayer resist method, a desiredthickness can be ensured by the lower-layer organic film, and as aresult, the thickness of the resist film can be reduced, and anextremely fine pattern with a high aspect ratio can be formed.

The multilayer resist method is broadly classified into a method inwhich a double-layer structure consisting of an upper-layer resist filmand a lower-layer organic film is formed (double-layer resist method),and a method in which a multilayer structure having at least threelayers consisting of an upper-layer resist film, a lower-layer organicfilm and at least one intermediate layer (thin metal film or the like)provided between the upper-layer resist film and the lower-layer organicfilm (triple-layer resist method).

The wavelength to be used for exposure is not particularly limited andthe exposure can be conducted using radiation such as ArF excimer laser,KrF excimer laser, F₂ excimer laser, extreme ultraviolet rays (EUV),vacuum ultraviolet rays (VUV), electron beam (EB), X-rays, and softX-rays. The resist composition of the present embodiment is effective toKrF excimer laser, ArF excimer laser, EB and EUV, and more effective toArF excimer laser, EB and EUV, and most effective to EB and EUV. Thatis, the method of forming a resist pattern according to the presentembodiment is effective in the case where the step of exposing theresist film includes exposing the resist film with extreme ultravioletrays (EUV) or electron beam (EB).

The exposure of the resist film can be either a general exposure (dryexposure) conducted in air or an inert gas such as nitrogen, orimmersion exposure (immersion lithography).

In immersion lithography, the region between the resist film and thelens at the lowermost point of the exposure apparatus is pre-filled witha solvent (immersion medium) that has a larger refractive index than therefractive index of air, and the exposure (immersion exposure) isconducted in this state.

The immersion medium preferably exhibits a refractive index larger thanthe refractive index of air but smaller than the refractive index of theresist film to be exposed. The refractive index of the immersion mediumis not particularly limited as long as it satisfies the above-mentionedrequirements.

Examples of this immersion medium which exhibits a refractive index thatis larger than the refractive index of air but smaller than therefractive index of the resist film include water, fluorine-based inertliquids, silicon-based solvents and hydrocarbon-based solvents.

Specific examples of the fluorine-based inert liquids include liquidscontaining a fluorine-based compound such as C₃HCl₂F₅, C₄F₉OCH₃,C₄F₉OC₂H₅ or C₅H₃F₇ as the main component, which have a boiling pointwithin a range from 70 to 180° C. and preferably from 80 to 160° C. Afluorine-based inert liquid having a boiling point within theabove-mentioned range is advantageous in that the removal of theimmersion medium after the exposure can be conducted by a simple method.

As a fluorine-based inert liquid, a perfluoroalkyl compound in which allof the hydrogen atoms of the alkyl group are substituted with fluorineatoms is particularly desirable. Examples of these perfluoroalkylcompounds include perfluoroalkylether compounds and perfluoroalkylaminecompounds.

Specifically, one example of a suitable perfluoroalkylether compound isperfluoro(2-butyl-tetrahydrofuran) (boiling point 102° C.), and anexample of a suitable perfluoroalkylamine compound isperfluorotributylamine (boiling point 174° C.).

As the immersion medium, water is preferable in terms of cost, safety,environment and versatility.

As an example of the alkali developing solution used in an alkalideveloping process, a 0.1 to 10% by weight aqueous solution oftetramethylammonium hydroxide (TMAH) can be given.

As the organic solvent contained in the organic developing solution usedin a solvent developing process, any of the conventional organicsolvents can be used which are capable of dissolving the component (A)(prior to exposure). Specific examples of the organic solvent includepolar solvents such as ketone solvents, ester solvents, alcoholsolvents, nitrile solvents, amide solvents and ether solvents, andhydrocarbon solvents.

A ketone solvent is an organic solvent containing C—C(═O)—C within thestructure thereof. An ester solvent is an organic solvent containingC—C(═O)—O—C within the structure thereof. An alcohol solvent is anorganic solvent containing an alcoholic hydroxy group in the structurethereof. An “alcoholic hydroxy group” refers to a hydroxy group bondedto a carbon atom of an aliphatic hydrocarbon group. A nitrile solvent isan organic solvent containing a nitrile group in the structure thereof.An amide solvent is an organic solvent containing an amide group withinthe structure thereof. An ether solvent is an organic solvent containingC—O—C within the structure thereof.

Some organic solvents have a plurality of the functional groups whichcharacterizes the aforementioned solvents within the structure thereof.In such a case, the organic solvent can be classified as any type of thesolvent having the characteristic functional group. For example,diethyleneglycol monomethylether can be classified as either an alcoholsolvent or an ether solvent.

A hydrocarbon solvent consists of a hydrocarbon which may behalogenated, and does not have any substituent other than a halogenatom. Examples of the halogen atom include a fluorine atom, a chlorineatom, a bromine atom and an iodine atom, and a fluorine atom ispreferable.

As the organic solvent contained in the organic developing solution,among these, a polar solvent is preferable, and ketone solvents, estersolvents and nitrile solvents are preferable.

Examples of ketone solvents include 1-octanone, 2-octanone, 1-nonanone,2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutylketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethylketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone,diacetonylalcohol, acetylcarbinol, acetophenone, methyl naphthyl ketone,isophorone, propylenecarbonate, γ-butyrolactone and methyl amyl ketone(2-heptanone). Among these examples, as a ketone solvent, methyl amylketone (2-heptanone) is preferable.

Examples of ester solvents include methyl acetate, butyl acetate, ethylacetate, isopropyl acetate, amyl acetate, isoamyl acetate, ethylmethoxyacetate, ethyl ethoxyacetate, propylene glycol monomethyl etheracetate, ethylene glycol monoethyl ether acetate, ethylene glycolmonopropyl ether acetate, ethylene glycol monobutyl ether acetate,ethylene glycol monophenyl ether acetate, diethylene glycol monomethylether acetate, diethylene glycol monopropyl ether acetate, diethyleneglycol monoethyl ether acetate, diethylene glycol monophenyl etheracetate, diethylene glycol monobutyl ether acetate, diethylene glycolmonoethyl ether acetate, 2-methoxybutyl acetate, 3-methoxybutyl acetate,4-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate,3-ethyl-3-methoxybutyl acetate, propylene glycol monomethyl etheracetate, propylene glycol monoethyl ether acetate, propylene glycolmonopropyl ether acetate, 2-ethoxybutyl acetate, 4-ethoxybutyl acetate,4-propoxybutyl acetate, 2-methoxypentyl acetate, 3-methoxypentylacetate, 4-methoxypentyl acetate, 2-methyl-3-methoxypentyl acetate,3-methyl-3-methoxypentyl acetate, 3-methyl-4-methoxypentyl acetate,4-methyl-4-methoxypentyl acetate, propylene glycol diacetate, methylformate, ethyl formate, butyl formate, propyl formate, ethyl lactate,butyl lactate, propyl lactate, ethyl carbonate, propyl carbonate, butylcarbonate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, butylpyruvate, methyl acetoacetate, ethyl acetoacetate, methyl propionate,ethyl propionate, propyl propionate, isopropyl propionate, methyl2-hydroxypropionate, ethyl 2-hydroxypropionate,methyl-3-methoxypropionate, ethyl-3-methoxypropionate,ethyl-3-ethoxypropionate and propyl-3-methoxypropionate. Among theseexamples, as an ester solvent, butyl acetate is preferable.

Examples of nitrile solvents include acetonitrile, propionitrile,valeronitrile, butyronitrile and the like.

If desired, the organic developing solution may have a conventionaladditive blended. Examples of the additive include surfactants. Thesurfactant is not particularly limited, and for example, an ionic ornon-ionic fluorine and/or silicon surfactant can be used.

As the surfactant, a non-ionic surfactant is preferable, and a non-ionicfluorine surfactant or a non-ionic silicon surfactant is morepreferable.

When a surfactant is added, the amount thereof based on the total amountof the organic developing solution is generally 0.001 to 5% by weight,preferably 0.005 to 2% by weight, and more preferably 0.01 to 0.5% byweight.

The developing treatment can be performed by a conventional developingmethod. Examples thereof include a method in which the substrate isimmersed in the developing solution for a predetermined time (a dipmethod), a method in which the developing solution is cast up on thesurface of the substrate by surface tension and maintained for apredetermined period (a puddle method), a method in which the developingsolution is sprayed onto the surface of the substrate (spray method),and a method in which the developing solution is continuously ejectedfrom a developing solution ejecting nozzle while scanning at a constantrate to apply the developing solution to the substrate while rotatingthe substrate at a constant rate (dynamic dispense method).

As the organic solvent contained in the rinse liquid used in the rinsetreatment after the developing treatment in the case of a solventdeveloping process, any of the aforementioned organic solvents containedin the organic developing solution can be used which hardly dissolvesthe resist pattern. In general, at least one solvent selected from thegroup consisting of hydrocarbon solvents, ketone solvents, estersolvents, alcohol solvents, amide solvents and ether solvents is used.Among these, at least one solvent selected from the group consisting ofhydrocarbon solvents, ketone solvents, ester solvents, alcohol solventsand amide solvents is preferable, more preferably at least one solventselected from the group consisting of alcohol solvents and estersolvents, and an alcohol solvent is particularly desirable.

The alcohol solvent used for the rinse liquid is preferably a monohydricalcohol of 6 to 8 carbon atoms, and the monohydric alcohol may belinear, branched or cyclic. Specific examples thereof include 1-hexanol,1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol,3-heptanol, 3-octanol, 4-octanol and benzyl alcohol. Among these,1-hexanol, 2-heptanol and 2-hexanol are preferable, and 1 hexanol and2-hexanol are more preferable.

As the organic solvent, one kind of solvent may be used alone, or two ormore kinds of solvents may be used in combination. Further, an organicsolvent other than the aforementioned examples or water may be mixedtogether. However, in consideration of the development characteristics,the amount of water within the rinse liquid, based on the total amountof the rinse liquid is preferably 30% by weight or less, more preferably10% by weight or less, still more preferably 5% by weight or less, andmost preferably 3% by weight or less.

If desired, the rinse solution may have a conventional additive blended.Examples of the additive include surfactants. Examples of the additiveinclude surfactants. As the surfactant, the same surfactants as thosedescribed above can be mentioned, a non-ionic surfactant is preferable,and a non-ionic fluorine surfactant or a non-ionic silicon surfactant ismore preferable.

When a surfactant is added, the amount thereof based on the total amountof the rinse liquid is generally 0.001 to 5% by weight, preferably 0.005to 2% by weight, and more preferably 0.01 to 0.5% by weight.

The rinse treatment using a rinse liquid (washing treatment) can beconducted by a conventional rinse method. Examples of the rinse methodinclude a method in which the rinse liquid is continuously applied tothe substrate while rotating it at a constant rate (rotational coatingmethod), a method in which the substrate is immersed in the rinse liquidfor a predetermined time (dip method), and a method in which the rinseliquid is sprayed onto the surface of the substrate (spray method).

In the method of forming a resist pattern according to the presentembodiment, the resist composition according to the first embodiment isused. Therefore, in the formation of a resist pattern, sensitivity maybe enhanced, and a resist pattern exhibiting good lithography properties(resolution performance, reduction of roughness, and the like) andhaving a good shape, e.g., high rectangularity, may be formed.

EXAMPLES

As follows is a description of examples of the present invention,although the scope of the present invention is by no way limited bythese examples.

In the following examples, a compound represented by a chemical formula(1) is denoted as “compound (1)”, and the same applies for compoundsrepresented by other chemical formulae.

Production Examples of Copolymers (A1-1-1) to (A1-1-17), Copolymers(A1-2-1) and (A1-2-2)

Each of copolymers (A1-1-1) to (A1-1-17), copolymers (A1-2-1) and(A1-2-2) was obtained by a conventional radical polymerization, usingmonomers for deriving the structural units that constitute eachcopolymer in a predetermined molar ratio.

The obtained copolymers (A1-1-1) to (A1-1-17), copolymers (A1-2-1) and(A1-2-2) are shown below.

With respect to each copolymer, the compositional ratio of the polymers(the molar ratio of the respective structural units in the polymericcompound) as determined by ¹³C-NMR, the weight average molecular weight(Mw) and the polydispersity (Mw/Mn) determined by the polystyreneequivalent value as measured by GPC are also shown in Table 1.

TABLE 1 Weight Compositional average ratio of molecular copolymer weightPolydispersity Copolymer (molar ratio) (Mw) (Mw/Mn) (A1-1-1) l/m = 50/506800 1.67 (A1-1-2) l/m = 50/50 7200 1.71 (A1-1-3) l/m = 50/50 6700 1.71(A1-1-4) l/m = 50/50 6700 1.72 (A1-1-5) l/m = 50/50 6700 1.71 (A1-1-6)l/m = 50/50 7000 1.72 (A1-1-7) l/m = 60/40 7000 1.71 (A1-1-8) l/m =50/50 6600 1.68 (A1-1-9) l/m = 50/50 6900 1.69 (A1-1-10) l/m/n =30/60/10 7000 1.71 (A1-1-11) l/m/n = 30/60/10 7000 1.64 (A1-1-12) l/m/n= 30/60/10 6900 1.64 (A1-1-13) l/m/n = 30/60/10 6800 1.67 (A1-1-14)l/m/n = 30/60/10 6800 1.62 (A1-1-15) l/m/n = 30/60/10 6600 1.69(A1-1-16) l/m/n = 30/60/10 6800 1.65 (A1-1-17) l/m/n = 30/60/10 67001.70 (A1-2-1) l/m = 50/50 7000 1.70 (A1-2-2) l/m = 50/50 7100 1.72

<Production of Resist Composition>

Examples 1 to 17, Comparative Examples 1 to 5

The components shown in Table 2 and 3 were mixed together and dissolvedto obtain each resist composition (solid content: 2.0% by weight).

TABLE 2 Component (B) Component Component Component Component Component(A) (B1) (B2) (D) (S) Example 1 (A1)-1 (B1)-1 — (D)-1 (S)-1 [100] [15.0][5.0] [6000] Example 2 (A1)-2 (B1)-1 — (D)-1 (S)-1 [100] [15.0] [5.0][6000] Example 3 (A1)-3 (B1)-1 — (D)-1 (S)-1 [100] [15.0] [5.0] [6000]Example 4 (A1)-4 (B1)-1 — (D)-1 (S)-1 [100] [15.0] [5.0] [6000] Example5 (A1)-5 (B1)-1 — (D)-1 (S)-1 [100] [15.0] [5.0] [6000] Example 6 (A1)-6(B1)-1 — (D)-1 (S)-1 [100] [15.0] [5.0] [6000] Example 7 (A1)-7 (B1)-1 —(D)-1 (S)-1 [100] [15.0] [5.0] [6000] Example 8 (A1)-8 (B1)-1 — (D)-1(S)-1 [100] [15.0] [5.0] [6000] Example 9 (A1)-9 (B1)-1 — (D)-1 (S)-1[100] [15.0] [5.0] [6000] Comparative (A1)-18 (B1)-1 — (D)-1 (S)-1Example 1 [100] [14.0] [5.0] [6000] Comparative (A1)-19 (B1)-1 — (D)-1(S)-1 Example 2 [100] [14.0] [5.0] [6000] Comparative (A1)-1 — (B2)-1(D)-1 (S)-1 Example 3 [100] [14.0] [5.0] [6000] Comparative (A1)-2 —(B2)-1 (D)-1 (S)-1 Example 4 [100] [14.0] [5.0] [6000] Comparative(A1)-1 — (B2)-2 (D)-1 (S)-1 Example 5 [100] [14.3] [5.0] [6000]

TABLE 3 Compo- Component (B) Compo- Compo- nent Component Component nentnent (A) (B1) (B1) (D) (S) Example (A1)-10 (B1)-1 — (D)-1 (S)-1 10 [100][15.0] [5.0] [6000] Example (A1)-11 (B1)-1 — (D)-1 (S)-1 11 [100] [15.0][5.0] [6000] Example (A1)-12 (B1)-1 — (D)-1 (S)-1 12 [100] [15.0] [5.0][6000] Example (A1)-13 (B1)-1 — (D)-1 (S)-1 13 [100] [15.0] [5.0] [6000]Example (A1)-14 (B1)-1 — (D)-1 (S)-1 14 [100] [15.0] [5.0] [6000]Example (A1)-15 (B1)-1 — (D)-1 (S)-1 15 [100] [15.0] [5.0] [6000]Example (A1)-16 (B1)-1 — (D)-1 (S)-1 16 [100] [15.0] [5.0] [6000]Example (A1)-17 (B1)-1 — (D)-1 (S)-1 17 [100] [15.0] [5.0] [6000]

In Tables 2 and 3, the reference characters indicate the following. Thevalues in brackets [ ] indicate the amount (in terms of parts by weight)of the component added.

(A1)-1 to (A1)-9: The above copolymers (A1-1-1) to (A1-1-9)

(A1)-10 to (A1)-17: The above copolymers (A1-1-10) to (A1-1-17)

(A)-18: The above copolymer (A1-2-1)

(A)-19: The above copolymer (A1-2-2)

(B1)-1: an acid generator represented by chemical formula (B1-1) shownbelow

(B2)-1: an acid generator represented by chemical formula (B2-1) shownbelow

(B2)-2: an acid generator represented by chemical formula (B2-2) shownbelow

(D)-1: Acid diffusion control agent represented by chemical formula(D-1) shown below.

(S)-1: a mixed solvent of propylene glycol monomethyl etheracetate/propylene glycol monomethyl ether=6/4 (weight ratio).

<Formation of Resist Pattern>

Step (i):

Each of the resist compositions of examples and comparative examples wasapplied to an 8-inch silicon substrate which had been treated withhexamethyldisilazane (HMDS) using a spinner, and was then prebaked (PAB)on a hot plate at 110° C. for 60 seconds and dried, thereby forming aresist film having a film thickness of 50 nm.

Step (ii):

A drawing (exposure) was carried out on the resist film using anelectron beam lithography system JEOL-JBX-9300FS (manufactured by JEOLLtd.) with acceleration voltage of 100 kV and a target size of 1:1line-and-space pattern (line width: 50 to 16 nm) (hereinafter referredto as an “LS pattern”). Then, a post exposure bake (PEB) treatment wasconducted at 90° C. for 60 seconds.

Step (iii)

Thereafter, alkali developing was conducted for 60 seconds at 23° C. ina 2.38% by weight aqueous solution of tetramethylammonium hydroxide(TMAH) (product name: NMD-3; manufactured by Tokyo Ohka Kogyo Co.,Ltd.).

Then, water rinsing was conducted for 15 seconds using pure water.

As a result, a 1:1 LS pattern having a line width of 50 to 16 nm wasformed.

[Evaluation of Optimum Exposure Dose (Eop)]

The optimum exposure dose Eop (μC/cm²) with which the LS pattern wasformed in the above formation of resist pattern was determined. Theresults are indicated under “Eop (μC/cm²)” in Tables 4 and 5.

[Evaluation of Resolution Performance]

The critical resolution (nm) with the above Eop was determined using ascanning electron microscope (product name: S-9380, manufactured byHitachi High-Technologies Corporation). Specifically, the exposure dosewas gradually increased from the optimum exposure dose Eop, and theminimum size of the pattern which resolves without collapse (fall) wasdetermined. The results are indicated under “Resolution performance(nm)” in Tables 4 and 5.

[Evaluation of Line Width Roughness (LWR)]

With respect to the LS pattern formed in the above “formation of resistpattern”, 3σ was determined as a yardstick for indicating LWR. Theresults are indicated under “LWR (nm)” in Tables 4 and 5.

“3σ” indicates a value of 3 times the standard deviation (o) (i.e., 3σ)(unit: nm) determined by measuring the line positions at 400 points inthe lengthwise direction of the line using a scanning electronmicroscope (product name: S-9380, manufactured by HitachiHigh-Technologies Corporation; acceleration voltage: 800V).

The smaller this 3σ value is, the lower the level of roughness on theside walls of the line, indicating that an LS pattern with a uniformwidth was obtained.

[Evaluation of LS Pattern Shape]

The cross-sectional shape of the LS pattern formed in the above“Formation of resist pattern” was observed using a lengthwise measuringSEM (scanning electron microscope; acceleration voltage: 800V; productname: SU-8000, manufactured by Hitachi High-Technologies Corporation),so as to evaluate the cross-sectional shape of the LS pattern.

The cross-sectional shape of the LS pattern was evaluated in accordancewith the following criteria. The results are indicated under “Shape” inTables 4 and 5.

Criteria for shape of LS pattern

A: Rectangular

B: Top-rounding (the top of the pattern is rounded)

TABLE 4 Resolution PAB PEB Eop LWR performance (° C.) (° C.) (μC/cm²)(nm) (nm) Shape Example 1 110 90 85 4.1 28 A Example 2 110 90 90 4.3 28A Example 3 110 90 88 4.3 26 A Example 4 110 90 89 4.2 28 A Example 5110 90 91 4.0 26 A Example 6 110 90 85 4.1 28 A Example 7 110 90 86 4.428 A Example 8 110 90 92 4.3 26 A Example 9 110 90 88 4.2 28 AComparative 110 90 142 5.5 50 B Example 1 Comparative 110 90 133 5.3 50B Example 2 Comparative 110 90 122 5.4 40 B Example 3 Comparative 110 90117 5.2 50 B Example 4 Comparative 110 90 155 5.8 50 A Example 5

TABLE 5 Resolution PAB PEB Eop LWR performance (° C.) (° C.) (μC/cm²)(nm) (nm) Shape Example 10 110 90 83 4.5 30 A Example 11 110 90 87 4.128 A Example 12 110 90 89 4.4 26 A Example 13 110 90 90 4.3 30 A Example14 110 90 88 4.3 28 A Example 15 110 90 92 4.2 28 A Example 16 110 90 864.4 30 A Example 17 110 90 84 4.5 28 A

A seen from the results shown in Tables 4 and 5, the resist compositionsof Examples 1 to 17 exhibited improved sensitivity, high resolutionperformance, and reduced roughness, as compared to the resistcompositions of Comparative Examples 1 to 5.

It was confirmed that the resist compositions of Examples 1 to 17 werecapable of enhancing the sensitivity, and forming a resist patternhaving a high rectangularity with improved lithography properties.

While preferred embodiments of the invention have been described andillustrated above, it should be understood that these are exemplary ofthe invention and are not to be considered as limiting. Additions,omissions, substitutions, and other modifications can be made withoutdeparting from the spirit or scope of the present invention.Accordingly, the invention is not to be considered as being limited bythe foregoing description, and is only limited by the scope of theappended claims.

What is claimed is:
 1. A resist composition which generates acid uponexposure and exhibits changed solubility in a developing solution underaction of acid, the resist composition comprising: a resin component(A1) which exhibits changed solubility in a developing solution underaction of acid, and an acid generator component (B) which generates acidupon exposure, wherein the resin component (A1) comprises a polymerhaving a structural unit (a0) in which a compound represented by generalformula (a0-1) has a polymerizable group within the W¹ portion convertedinto a main chain, and the acid generator component (B) comprises acompound represented by general formula (b1-1) shown below, and X⁻ is ananion represented by general formula (b1-1-an1) shown below, an anionrepresented by general formula (b1-1-an2) shown below, or an anionrepresented by general formula (b1-1-an3) shown below:

wherein in formula (a0-1), W¹ represents a polymerizablegroup-containing group; C^(t) represents a tertiary carbon atom, and theα-position of C^(t) is a carbon atom which constitutes a carbon-carbonunsaturated bond; R¹¹ represents an aromatic hydrocarbon group which mayhave a substituent, or a chain hydrocarbon group; R¹² and R¹³ aremutually bonded to form a 5-membered aliphatic monocyclic groupoptionally having a substituent, or a condensed polycyclic hydrocarbongroup containing a 5-membered aliphatic monocyclic ring, the condensedpolycyclic hydrocarbon group optionally having a substituent; in formula(b1-1), R^(b11) represents a cyclic group which may have a substituent;R^(b10), R^(b20) and R^(b30) each independently represents asubstituent; n_(b1) represents an integer of 0 to 4; n_(b2) representsan integer of 0 to 5; n_(b3) represents an integer of 0 to 5; X⁻represents a counteranion, and in formulae (b1-1-an1), (b1-1-an2), and(b1-1-an3), R¹⁰¹ and R¹⁰⁴ to R¹⁰⁸ each independently represents a cyclicgroup which may have a substituent, a chain-like alkyl group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent, provided that R¹⁰⁴ and R¹⁰⁵ may be mutually bonded to forma ring structure; R¹⁰² represents a fluorine atom or a fluorinated alkylgroup having 1 to 5 carbon atoms; Y¹⁰¹ represents a single bond or adivalent group containing an oxygen atom; V¹⁰¹ to V¹⁰³ eachindependently represents a single bond, an alkylene group or afluorinated alkylene group; L¹⁰¹ and L¹⁰² each independently representsa single bond or an oxygen atom; and L¹⁰³ to L¹⁰⁵ each independentlyrepresents a single bond, —CO— or —SO₂—.
 2. The resist compositionaccording to claim 1, wherein the amount of the structural unit (a0)based on the combined total (100 mol %) of all structural unitsconstituting the polymeric compound is 40 mol % or more.
 3. The resistcomposition according to claim 1, wherein—C^(t)(R¹¹)(R¹²)(R¹³) ingeneral formula (a0-1) is a group represented by general formula(a0-r-1) shown below, a group represented by general formula (a0-r-2)shown below or a group represented by general formula (a0-r-3) shownbelow:

wherein, in formula (a0-r-1), Ra′¹¹⁰ represents a linear or branchedalkyl group having 1 to 12 carbon atoms optionally having part thereofsubstituted with a halogen atom or a hetero atom-containing group;Ra′¹¹¹ represents a group which forms a 5-membered aliphatic monocyclicgroup together with the carbon atom to which Ra′¹¹⁰ is bonded, or agroup which forms a condensed polycyclic hydrocarbon group containing a5-membered aliphatic monocyclic ring together with the carbon atom towhich Ra′¹¹⁰ is bonded; in Ra′¹¹¹, the α-position of the tertiary carbonatom to which Ra′¹¹⁰ is bonded is a carbon atom which constitutes acarbon-carbon unsaturated bond; provided that part or all of thehydrogen atoms of the 5-membered aliphatic monocyclic group or thecondensed polycyclic hydrocarbon group may be substituted; in formula(a0-r-2), C^(t) represents a tertiary carbon atoms; Xa represents agroup which forms a 5-membered aliphatic monocyclic group together withC^(t); provided that part or all of the hydrogen atoms of the 5-memberedmonocyclic aliphatic hydrocarbon group may be substituted; Ra⁰¹ to Ra⁰³each independently represents a hydrogen atom, a monovalent saturatedchain hydrocarbon group of 1 to 10 carbon atoms or a monovalentsaturated aliphatic cyclic hydrocarbon group of 3 to 20 carbon atoms;provided that part or all of the hydrogen atoms of the saturated chainhydrocarbon or the saturated aliphatic cyclic hydrocarbon may besubstituted; 2 or more of Ra⁰¹ to Ra⁰³ may be mutually bonded to form analiphatic cyclic structure, but does not form a bridged structure; informula (a0-r-3), C^(t) represents a tertiary carbon atoms; Xaarepresents a group which forms a 5-membered aliphatic monocyclic grouptogether with C^(t); provided that part or all of the hydrogen atoms ofthe 5-membered monocyclic aliphatic hydrocarbon group may besubstituted; Ra⁰⁴ represents an aromatic hydrocarbon group which mayhave a substituent; * represents a bonding site.
 4. The resistcomposition according to claim 2, wherein—C^(t)(R¹¹)(R¹²)(R¹³) ingeneral formula (a0-1) is a group represented by general formula(a0-r-1) shown below, a group represented by general formula (a0-r-2)shown below or a group represented by general formula (a0-r-3) shownbelow:

wherein, in formula (a0-r-1), Ra′¹¹⁰ represents a linear or branchedalkyl group having 1 to 12 carbon atoms optionally having part thereofsubstituted with a halogen atom or a hetero atom-containing group;Ra′¹¹¹ represents a group which forms a 5-membered aliphatic monocyclicgroup together with the carbon atom to which Ra′¹¹⁰ is bonded, or agroup which forms a condensed polycyclic hydrocarbon group containing a5-membered aliphatic monocyclic ring together with the carbon atom towhich Ra′¹¹⁰ is bonded; in Ra′¹¹¹, the α-position of the tertiary carbonatom to which Ra′¹¹⁰ is bonded is a carbon atom which constitutes acarbon-carbon unsaturated bond; provided that part or all of thehydrogen atoms of the 5-membered aliphatic monocyclic group or thecondensed polycyclic hydrocarbon group may be substituted; in formula(a0-r-2), C^(t) represents a tertiary carbon atoms; Xa represents agroup which forms a 5-membered aliphatic monocyclic group together withC^(t); provided that part or all of the hydrogen atoms of the 5-memberedmonocyclic aliphatic hydrocarbon group may be substituted; Ra⁰¹ to Ra⁰³each independently represents a hydrogen atom, a monovalent saturatedchain hydrocarbon group of 1 to 10 carbon atoms or a monovalentsaturated aliphatic cyclic hydrocarbon group of 3 to 20 carbon atoms;provided that part or all of the hydrogen atoms of the saturated chainhydrocarbon or the saturated aliphatic cyclic hydrocarbon may besubstituted; 2 or more of Ra⁰¹ to Ra⁰³ may be mutually bonded to form analiphatic cyclic structure, but does not form a bridged structure; informula (a0-r-3), C^(t) represents a tertiary carbon atoms; Xaarepresents a group which forms a 5-membered aliphatic monocyclic grouptogether with C^(t); provided that part or all of the hydrogen atoms ofthe 5-membered monocyclic aliphatic hydrocarbon group may besubstituted; Ra⁰⁴ represents an aromatic hydrocarbon group which mayhave a substituent; * represents a bonding site.
 5. The resistcomposition according to claim 1, wherein the polymeric compound furthercomprises a structural unit represented by general formula (a0-2) shownbelow:

wherein W² represents a polymerizable group-containing group; Wa^(x0)represents a (n_(ax0)+1)-valent cyclic group having aromaticity andoptionally having a substituent; Wa^(x0) may form a condensed ringtogether with W²; and n_(ax0) represents an integer of 1 to
 3. 6. Theresist composition according to claim 2, wherein the polymeric compoundfurther comprises a structural unit represented by general formula(a0-2) shown below:

wherein W² represents a polymerizable group-containing group; Wa^(x0)represents a (n_(ax0)+1)-valent cyclic group having aromaticity andoptionally having a substituent; Wa^(x0) may form a condensed ringtogether with W²; and n_(ax0) represents an integer of 1 to
 3. 7. Theresist composition according to claim 3, wherein the polymeric compoundfurther comprises a structural unit represented by general formula(a0-2) shown below:

wherein W² represents a polymerizable group-containing group; Wa^(x0)represents a (n_(ax0)+1)-valent cyclic group having aromaticity andoptionally having a substituent; Wa^(x0) may form a condensed ringtogether with W²; and n_(ax0) represents an integer of 1 to
 3. 8. Theresist composition according to claim 4, wherein the polymeric compoundfurther comprises a structural unit represented by general formula(a0-2) shown below:

wherein W² represents a polymerizable group-containing group; Wa^(x0)represents a (n_(ax0)+1)-valent cyclic group having aromaticity andoptionally having a substituent; Wa^(x0) may form a condensed ringtogether with W²; and n_(ax0) represents an integer of 1 to
 3. 9. Theresist composition according to claim 1, wherein the acid generatorcomponent (B) comprises a compound represented by general formula(b1-10) shown below:

wherein R¹⁰¹ represents a cyclic group which may have a substituent, achain alkyl group which may have a substituent or a chain alkenyl groupwhich may have a substituent; Y¹⁰¹ represents a single bond or adivalent group containing an oxygen atom; V¹⁰¹ represents a single bond,an alkylene group or a fluorinated alkylene group; R¹⁰² represents afluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms;R^(b11) represents a cyclic group which may have a substituent; R^(b10),R^(b20) and R^(b30) each independently represents a substituent; n_(b1)represents an integer of 0 to 4; n_(b2) represents an integer of 0 to 5;and n_(b3) represents an integer of 0 to
 5. 10. The resist compositionaccording to claim 2, wherein the acid generator component (B) comprisesa compound represented by general formula (b1-10) shown below:

wherein R¹⁰¹ represents a cyclic group which may have a substituent, achain alkyl group which may have a substituent or a chain alkenyl groupwhich may have a substituent; Y¹⁰¹ represents a single bond or adivalent group containing an oxygen atom; V¹⁰¹ represents a single bond,an alkylene group or a fluorinated alkylene group; R¹⁰² represents afluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms;R^(b11) represents a cyclic group which may have a substituent; R^(b10),R^(b20) and R^(b30) each independently represents a substituent; n_(b1)represents an integer of 0 to 4; n_(b2) represents an integer of 0 to 5;and n_(b3) represents an integer of 0 to
 5. 11. The resist compositionaccording to claim 3, wherein the acid generator component (B) comprisesa compound represented by general formula (b1-10) shown below:

wherein R¹⁰¹ represents a cyclic group which may have a substituent, achain alkyl group which may have a substituent or a chain alkenyl groupwhich may have a substituent; Y¹⁰¹ represents a single bond or adivalent group containing an oxygen atom; V¹⁰¹ represents a single bond,an alkylene group or a fluorinated alkylene group; R¹⁰² represents afluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms;R^(b11) represents a cyclic group which may have a substituent; R^(b10),R^(b20) and R^(b30) each independently represents a substituent; n_(b1)represents an integer of 0 to 4; n_(b2) represents an integer of 0 to 5;and n_(b3) represents an integer of 0 to
 5. 12. The resist compositionaccording to claim 4, wherein the acid generator component (B) comprisesa compound represented by general formula (b1-10) shown below:

wherein R¹⁰¹ represents a cyclic group which may have a substituent, achain alkyl group which may have a substituent or a chain alkenyl groupwhich may have a substituent; Y¹⁰¹ represents a single bond or adivalent group containing an oxygen atom; V¹⁰¹ represents a single bond,an alkylene group or a fluorinated alkylene group; R¹⁰² represents afluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms;R^(b11) represents a cyclic group which may have a substituent; R^(b10),R^(b20) and R^(b30) each independently represents a substituent; n_(b1)represents an integer of 0 to 4; n_(b2) represents an integer of 0 to 5;and n_(b3) represents an integer of 0 to
 5. 13. The resist compositionaccording to claim 5, wherein the acid generator component (B) comprisesa compound represented by general formula (b1-10) shown below:

wherein R¹⁰¹ represents a cyclic group which may have a substituent, achain alkyl group which may have a substituent or a chain alkenyl groupwhich may have a substituent; Y¹⁰¹ represents a single bond or adivalent group containing an oxygen atom; V¹⁰¹ represents a single bond,an alkylene group or a fluorinated alkylene group; R¹⁰² represents afluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms;R^(b11) represents a cyclic group which may have a substituent; R^(b10),R^(b20) and R^(b30) each independently represents a substituent; n_(b1)represents an integer of 0 to 4; n_(b2) represents an integer of 0 to 5;and n_(b3) represents an integer of 0 to
 5. 14. The resist compositionaccording to claim 6, wherein the acid generator component (B) comprisesa compound represented by general formula (b1-10) shown below:

wherein R¹⁰¹ represents a cyclic group which may have a substituent, achain alkyl group which may have a substituent or a chain alkenyl groupwhich may have a substituent; Y¹⁰¹ represents a single bond or adivalent group containing an oxygen atom; V¹⁰¹ represents a single bond,an alkylene group or a fluorinated alkylene group; R¹⁰² represents afluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms;R^(b11) represents a cyclic group which may have a substituent; R^(b10),R^(b20) and R^(b30) each independently represents a substituent; n_(b1)represents an integer of 0 to 4; n_(b2) represents an integer of 0 to 5;and n_(b3) represents an integer of 0 to
 5. 15. The resist compositionaccording to claim 7, wherein the acid generator component (B) comprisesa compound represented by general formula (b1-10) shown below:

wherein R¹⁰¹ represents a cyclic group which may have a substituent, achain alkyl group which may have a substituent or a chain alkenyl groupwhich may have a substituent; Y¹⁰¹ represents a single bond or adivalent group containing an oxygen atom; V¹⁰¹ represents a single bond,an alkylene group or a fluorinated alkylene group; R¹⁰² represents afluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms;R^(b11) represents a cyclic group which may have a substituent; R^(b10),R^(b20) and R^(b30) each independently represents a substituent; n_(b1)represents an integer of 0 to 4; n_(b2) represents an integer of 0 to 5;and n_(b3) represents an integer of 0 to
 5. 16. The resist compositionaccording to claim 8, wherein the acid generator component (B) comprisesa compound represented by general formula (b1-10) shown below:

wherein R¹⁰¹ represents a cyclic group which may have a substituent, achain alkyl group which may have a substituent or a chain alkenyl groupwhich may have a substituent; Y¹⁰¹ represents a single bond or adivalent group containing an oxygen atom; V¹⁰¹ represents a single bond,an alkylene group or a fluorinated alkylene group; R¹⁰² represents afluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms;R^(b11) represents a cyclic group which may have a substituent; R^(b10),R^(b20) and R^(b30) each independently represents a substituent; n_(b1)represents an integer of 0 to 4; n_(b2) represents an integer of 0 to 5;and n_(b3) represents an integer of 0 to
 5. 17. A method of forming aresist pattern, comprising: forming a resist film using the resistcomposition according to claim 1; exposing the resist film; anddeveloping the exposed resist film to form a resist pattern.
 18. Theresist pattern forming method according to claim 17, wherein the resistfilm is exposed to extreme ultraviolet (EUV) or electron beam (EB).